Hi, I'm posting looking for help for my dad. He just bought a 2000 Grand Prix GTP Sedan about 2 weeks ago at most, and is already having trouble with it. The car is from Michigan, but we bought it in PA not too far from the NY/PA border. The car is very clean for it's age, and only has 85,000 miles. The car was a one owner (female) that only made 2 mile trips daily, and once in awhile from Michigan to PA where we live.
The first day of having the car it ran great other than a little stumble I heard when he fired first fired it up. Pulled real strong throughout the rev range, no hiccups at all. Brought it home and later went out to drive it again, car immediately became sluggish and had a hesitation. Threw a SES code for the MAF.
Picked up a MAF, installed it, along with a new supercharger tensioner as it was quite noisy. The SES went away and has not come back, but the car still has a major hesitation between 3800 - 4800 rpm area. Almost as if it's hitting a rev limiter. The car bucks, sputters, hesitates, then picks back up again after that 3800 - 4800 rpm range and runs decent, but still feels down on power up to redline. When you aren't WOT, the car doesn't do this at all.
My dad thinks it's a fuel delivery issue, such as a clogged fuel filter and we're about to put that on now. If that does not fix it, what other item should we look into?
The car is stock as far as we know, other than the stock resonator/mid muffler was removed and replaced with a straight pipe as it was rotten.
