The spark plugs in your engine have NO Sealing Washer.
They have a Tapered Seat,,which seals metal to metal into a tapered surface on the cylinder head.
Most cars have used that type of spark plug for many years.
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Leaking spark plug seal can be caused by a few things.
*Damaged Seat on the head
*Very Common is "Debris" ,,,a Dirty spark plug seat on the head.
*Also very common is "False Torque".
This is where Plug FEELS tight,,,but not actually Seated.
--reasons can be:
>Dirty Seat
>Damaged Threads on Plug or Head(not Stripped,,but Tight
>Carbon in Threads
*Its also EASY to BREAK a spark plug.
Wrong type of Socket breaks them easily.
"Tilting Wrench" also breaks them
Over Tightening them can break them
---It can happen at time of installation
---It can cause them to break later,,once engine runs a while
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An experienced person can "feel" the correct spark plug Torque surprisingly close.
Even so,,,,Proper Torque(Installation Tightness) is IMPORTANT for a variety of reasons.
Best Bet is to use a Torque Wrench.
Even a Cheap one is better than a Bad Guess.
$10~15 maybe???
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I'd suggest getting a new set of spark plugs
AND a cheap Torque Wrench
AND make certain to use an actual Spark Plug Socket.
"DeepWell or Long" Sockets will Fit,,they'll work,
But they are VERY easy to break a spark plug with.
Clean the area around the holes very well
Put some motor oil or transmission fluid on the Plugs' Threads And the sealing taper seat.
Take care to not let "oiled plugs" touch anything dirty /gritty as you position them into place.
When Tightening them make sure to hold wrench/socket
directly square and straight on the Plug.
Tilting the wrench when Tightening them,,,breaks them.
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Putting Gas in Spark Plug hole is BAD IDEA.
It's a STUPID shade-tree trick which accomplishes NOTHING USEFUL.
Zillions of people do it.
If an engine ain't getting Fuel,,,why risk a FIRE,,or Hydraulic Lock Damage or effectively filling exhaust system with Raw Fuel?
Just to hear it TRY to start and fall dead?
It's nothing but a Risky waste of time.
And does NOTHING to fix anything.
It just makes whoever "Feel Better" when they hear the engine sputter and try to run for a second.
And,,there's not many better ways to RUIN a spark plug.
The raw fuel washes all the oil off the cylinder,,and some of the greasy soft-carbon deposits.
Then the piston splashes &squeezes that greasy oily "mud" all over the Spark Plug---which is impossible to fire thru.
When the Electricty TRIES,,,it cooks all that crap onto the plug.
As engine motors over,,,it clears the raw fuel Out till it drops to a combustible level.
Plug begins to Intermittently fire.
That finishes baking the crap onto the plug.
But,,Just Like any other kind of Murder.....
people get away with doing it.
Whether the Plug Survives or Not,,,ya done beat the hell outa it.
And next many miles will be spent trying to Clean Itself,,rather than doing it's Real Job>>run the engine.
It's an old myth started back in Pre-Model T era when nobody knew anything about engines.
On-lookers were fascinated by the "Motoring Expert's Magical Trick"
Nothing but a waste of time.
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If Car was running basically OK,,,BEFORE fooling with the plugs....
Then New Plugs Installed properly should get you back to square one..
It oughta at least go back to running the way it was Before.
DOUBLE CHECK that the Spark Plug Wires are connected to the Correct Spark Plugs.
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Sluggish Starting ,,the "original problem">>>
That can be caused by a Bunch of things.
It's almost "Normal" on a 10 year old car,,even if it's not RIGHT.
All the various things involved total-up over time to make an engine system not quite as sharp as a New One.
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FUEL SYSTEM:
Fuel Injection systems get a bit dirty and internally bleed off fuel pressure when car sits overnite.
They're Supposed to hold FULL pressure for an extended time when engine is shut down,,,so engine will re-start "instantly".
There's a Check Valve that can leak,,,and the Injector Nozzles themselves.
It takes the Fuel Pump several seconds to Re-Pressurize the system and Start the engine.
EASIEST,CHEAPEST thing to try.
Fill Up with Premium Fuel,,,Chevron Premium is By FAR the BEST.
Simple Reason>the TYPE and Concentration and CONSISTENCY of CLEANERS in the Additive package.
Chevron Premium is damn near being a TOOL to "fix" some injection conditions.
So spend the extra $5/Tank to fill up with Premium Fuel>Chevron if you can.
AND,,go to any Auto Parts store and get a bottle of Chevron Techron Fuel Injection Cleaner,,,about $8~10 i guess.
Pour that in.
There's all sorts of Good Fuel System Cleaners.
I do not use Techron normally cuz it's so expensive.
I "Keep" fuel system cleaner in my gas tank---comes from the Dollar Stores we have all over my town.
$1/Bottle,,,a Years worth for price of 1 Techron.
But when I want to try to " FIX" a troubled fuel injection system,,,
by just pouring some crap into the gas tank,,
Techron is the only thing I'll use
Not so much because it's necessarily THE Best.
But because it's the most consistent.
Certain Fuel Systems prefer certain cleaners.
Some Cleaners dont help Certain cars much at all.
I know what Techron does,and what to expect.
Which makes it a sort of "experimental CONSTANT" in whatever system is being worked on.
If Problem persists,,then I know to look elsewhere
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IGNITION Probs>
Plugs,,we know about
Plug Wires last an amazing long time these days,,,but they "Fade" out of Specs in many cases.
They still Work,,,but not 100% Right,,and Can cause sluggish starting.
On a 10 yr old car,,,Plugs and Wires need to be Fresh.
That's the Beginning of troubleshooting Starting Probs.
May NOT help,,or May be the actual solution.
Either way,,,they NEED to be Right.
Coils,Crank Sensor,Ignition Module may also be at fault or a contributor to difficulty.
Testing & Verifying those are best left to a knowledgeable,experienced person.
Trial & Error gets expensive.
New Parts never HURT....
but it may be an expense which doesnt solve the actual problem.
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BATTERY
Everybody Knows when a Battery is Bad.
We all know what a DEAD Battery acts like.
But a DYING battery is not so obvious.
They'll crank the car,,start and run,and can go for many,many MONTHS like that.
But they can also make a car tricky to start.
A WEAK battery nearing end of it's life loses CRANKING Capacity.
It MAY seem to crank plenty good enough.
But it MIGHT also produce Low Voltage when cranking>
to Ignition System,
Fuel Pump,
Engine Control ECU and all the various sensors.
Easily Possible for effects of Low Cranking Voltage to all total-up and make for a car that doesnt start quite as Sharp & Crisp as it should.
ANY Car Battery after about 2 Years can be considered "Upper Middle Age" and begiining the Downhill side of it's life.
SURE,,they Go LOTS Longer,3~4Yrs Total,,5,6 yrs.
I've had some plain,ordinary car batteries last almost 10 years.
But as a matter of the CHEMISTRY of Batteries,,,Between 2 & 3 years they begin to Decline.
We do not sense that,,,
because most Batteries are "Falling" from So Much Higher up the scale of our car's REQUIREMENTS.
Example:
Car may require 50 Amps,,and will work on 40 pretty good.
An 80 Amp Batt deteriorated to 60 Amps is 25% GONE.
Yet it's Still 20% ABOVE our cars' Optimum requirement.
At 40A,,the 80A Batt is Half DEAD,Half Garbage,,it's History.
But it STILL meets the Minimum of our car,,,so Car works OK and all seems fine.
Noticeable probs may not apear till Batt is 60~75% depleted.
Electrical Devices draw more Current as Voltage DROPS.
So a Starter Motor that requires X-Voltage and draws X-Amps,,,,
When Voltage is Low or Amp Capacity is Low,,,,
It turns into an even HUNGRIER motor.
It wants MORE than Normal,,Normal is no longer Good Enough.
It's Weird and takes a bit of thought to get the idea.
Proper SUPPLY to a Certain Demand = OK
LOWER Supply creates an even HIGHER Demand.
The Difference is NOT just the Deficit between the 2 standard Specs.
The LOAD DEMAND rises,,,making the Shortcoming an even GREATER PERCENTAGE that the Specs & Numbers suggest
12V Motor needs 40 Amps for example
Drop Voltage to 10 or 11,,,it may want 50 Amps.
Electrical Engineers can explain all that by Formula,,it's a property which they use everyday to design/troubleshoot stuff.
To the rest of us just trying to use our car,,
the EFFECT is experienced as>>
One Day our car seems to be fine,,,next time we try to start it,,it WONT even TRY to start/crank.
Bump it with a Jumper Cable,or put a new Battery and VROOOMMM!!!,,,it' starts as Strong as ever.
Batts decline a Looong Time,,,beginning the FIRST time ya use it.
Till One Day,,,it just falls off a cliff and dies.
Starter Motors gradually Degrade a bit over time.
Their Demand Rises as that happens.
RESULT of all that is sluggish starting.
Easy way to determine if that's anything "Battery Related",,,
"Curable" with a new Battery?
Get another Car and jump start yours.
If it cranks and starts real quick,strong and zoomy....
Time for a New Battery.
I realize that's WAAAY too much speech to say,,
"Check the Battery" or "Try a new Battery"
But as I said in the beggining....
Nobody needs to be told "Battery's DEAD",,,we all Know when that happens.
Not too many people fully understand that Batteries are "DYING" from Day One,,,how that Acts,,and what it means to Them.
Or how to tell Ahead of Time when it's time to Change it.
WEAK Battery is BAD NEWS,,it puts an extra load on EVERYTHING from Fuses to Radio Circuitry to Light Bulbs,,,A/C Fan,,,,everything.
Cars have a 12V NOMINAL system.
Most Batteries make 13~13.5~up to 14.5 Volts
11.5 Volts is harder on a 12V system than 14.5 Volts,,because of the extra amperage it demands & draws.
When a Batt is "worn out" and cannot supply that Amperage,,,Voltage drops even FURTHER.
A GOOD Batt with Low Voltage---from leaving lights on or whatever,,,has the AMP capacity to serve the deficit.
So it really doesnt hurt anything and it's only temporary.
Soon as engine starts,,all is back to normal soon enough.
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Anyway,,,,for a weak Starting prob the things you can do without actually getting into Serious Diagnostic Effort
*Try a tank of HiDetergent Premium Fuel
and Add some Fuel Inject Cleaner
*Put some New plugs in,,and some new spark Plug wires
*Even though your battery seems fine,,,,
Try Jump Starting the car and see if that makes it start real quick,,,or any noticeable amount quicker.
If it Does,,,your battery is trying to tell ya something.
It may "last" 6 months or a year and do "good enough".
But if the "jump start test" shows an improvement in how quick the engine starts & runs,,,
only thing that'll fix that is "More Power" from the battery.
You just proved it,,according to the results you observe by jump starting it.
(Goes without saying,,Battery Cables/Connections need to be VERY Clean. Even if it works OK,,any corrosion is a Semi-Conductor Resistance and reduces USEABLE amperage.
Just like turning down a water faucet a little bit---it's a Restriction between SUPPLY and Demand)
Subtle,marginal Starting Probs can be Tuff.
It's WORKING,,,but just not quite right.
Logically,,the CAUSE will be a subtle slip from required specs.
Nothing's really BROKEN,,,just "off" a bit.
Ya can't change EVERTHING,,
Best you can do is start with the easy,routine stuff.
All that needs to be Right anyway.
If that dont help,,,then you go on to "hardcore,serious" trouble shooting.
And at some point,,you have to decide that while it may not be Ideal/Perfect/Like New,,,,,ya gotta decide what's good Enough & acceptible.
And again,,I dont care what anyone thinks....
DONT POUR GASOLINE DOWN SPARK PLUG HOLE.
Yeah,,it's been done a BILLION Times by Millions of people.
But there's NOTHING to GAIN.
And it has the Distinct Potential to cause some Serious damage to Car And People in a variety of ways.
ALL Risk,NO Reward is always a game that can ONLY be won by NOT PLAYING.
Good Luck,,hope it's nothing more serious.
+++Ohh,,I forgot something important to check
The "Air Noise" may NOT be a leaky spark plug at all.
Might be a Vacuum Hose,,that's cracked or broken or pulled off it's fitting.
It may have been that way for a while,,,or could have happened while working on the car.
Ya REALLY need to find the source of that noise,,,and check carefully that all the small vacuum hoses are in place and not damaged /leaking in any way.
Not as easy as it sounds,,they can be hard to see.
Even a Small air leak can make an engine start /run TERRIBLE depending on what's leaking.
A Tiny crack in a vac hose can cause it to run as bad as any Major Component failure.
Dont just Glance and take it for granted that "it Looks Ok".
Be Thorough in verifying their integrity