if the plug doesn't light up on the 1st 2 or 3 coils then it is a bad plug.

I ure still having the problem when you press the throttle 1/3rd of the way and it moves slowly then try checking that your brake isn't on. If you can move the car back wards and forward when the engine isn't on then its most probably the brake isn't set properly.

Change the trim on your controller to full throttle (when the engine isn't on) and see if you can roll the car then. if you can loosen out the brake.[8D]