while accelerating from a dead stop, the car bucks and jerks but recovers afterwards. it also happens when i need power to overtake, if i step on the gas pedal, it feels like the car stutters (i have to let go off the pedal slightly for it to recover). engine light was on but after the crankcase was flushed, it went away. i was told by firestone that i need to replace the engine coil, a spark plug and a plentum gasket? any help with this issue?