Engine Performance problem
2004 Pontiac Grand Prix 6 cyl Two Wheel Drive Automatic 156000 miles
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My 2004 Grand Prix will hesitate when accelerating on a hill or under a slight load. happens from a stop or at speed. on ramp to highways with a slight incline will cause the hesitation. recently had tuneup, oil change and changed fuel filter. used injector cleaner 3 times
with no difference..

should solve yuor problem. See post from "the kidd" on this site.