It could be the way you are using your brake and clutch together.
If you have a tachometer, watch your engine speed as you brake. Normally with a manual transmission you brake first and use the clutch to disengage the transmission before the engine RPM decreases significantly.
You may need to adjust the idle speed. If there are certain conditions that seem to be common when the engine dies, you might see if it happens during hot weather, cold weather, etc.
It also could indicate a vacuum leak.
If the warranty has expired you have no legal hold on your dealer, but many dealers might see what they can do just to keep your good will. It never hurts to ask.
I have the problem occasionally with my Isuzu Amigo, but it usually is a problem I have on a very hot day, and I attribute it to the effect of heat on my fuel flow. I could be wrong. The car usually runs pretty well, so I don't worry about it.