So since I have owned my 04 grand prix gt I have not been able to figure this out, driving aggressive or accelerate quick for a little bit, calm back down a d hen get behind someone slow, accelerate to pass, car looses power, cuts in an out. 50/50 it stalls, feathering the gas or backing off a little helps sometimes. Wont start until the key ha been turned off and the door opened. Had a mechanic down here tell me its the throttle positioning sensor... changed it, no change.... not sure if this is part of the problem also but she doesnt like 3rd gear neither. Accelerate normally and it will hold 2nd till 4000 rpms, let off the gas a little bit and it will shift at 60 kmph into 4th, any pressure change in the pedal and downshifts again. Climbing hills loves to drop into second even when its completely unnecessary. Any thoughts greatly appreciated thanks