A P0300 code is indeed for a "random misfire'. The computer monitors the crankshaft speed, and has noticed a variation in that crankshaft speed that fits a misfire parameter. However, the speed variation was intermittent enough, or didn't last long enough, to pinpoint a particular cylinder as being the culprit. That's true as far as the federal misfire parameters are concerned. HOWEVER, there is a way to access the actual engineering data using almost any scanner that will identify the cylinder(s) causing the problem. Using "Mode 6" in the scan tool and accessing the data available can be extremely helpful. The misfire can be ignition, fuel, or mechanical, but from what you are describing, I'd put my money on fuel. A slightly restricted injector is the most common cause if it misfires only on initial startup, at least in MY experience,BUT I also have concerns over the secondary ignition parts that are still original. Although it is true that Ford recommends 100,000 mile parts replacement intervals, the fine print dictates "under normal driving conditions". Delving further into those definitions shows that, according to Ford, there are NO normal driving conditions. Everywhere in the country its either too hot, too cold, too dry, too wet, too high, too low-you get the idea. I personally recommend replacing the secondary ignition components at about 60,000 miles to avoid having an issue with parts seizing in aluminum heads and causing problems. And for my last point, I NEVER recommend driving a vehicle any longer than absolutely necessary with a warning lamp on. While 95% of the causes for a Service Engine Soon lamp won't harm anything, there are those things that the SES lamp is the first indication that something is being hurt, and with it already on for another harmless reason......you get the idea. Remember, that light is supposed to be illuminated when the vehicle is exceeding the Federal emissions standards by 1 1/2 times.