3100 Grand Prix 2000 model hesitation at 2500 rpms

[MRJFieroGT]

Hey guys I'm trying to get my new used car up to par here. At 2500 rpms it shutters. If it goes above 3000 rpms then it seems fine but anywhere between it hesitates.

i have changed the plugs, wires, fuel pressure regulator, fuel rail, fuel injectors, crank sensor at the pulley wheel, oil, oil filter, fuel filter, tranny filter and tranny fluid, coil packs and the coil block, map sensor. I've put seafoam into the intake and cleaned it all out.

What really am I missing? It was doing this before the plugs and wires change and it just hasn't helped. Can anyone help me? THanks in advance. . .

Matt Jackson

[SappySE107]

TPS sensor, MAF sensor, grounds, computer. A scan of the computer might be cheaper to obtain but you have already replaced pretty much everything else.

[MRJFieroGT]

I've had the computer scanned at Advance Auto Parts. All they said was that it was a multiple misfire. They did have a cause of it. That and a couple other codes that I've taken care of already.

I mean I could change everything but I'm tired of doing that.

[MRJFieroGT]

I've changed the MAF and the two sensors in the throttle body. Could a blockage in the exhaust be cause this problem? I'm just trying to figure this out on my own. Thanks
Matt J

[bszopi]

Yeah, a bad catalytic converter can cause issues like that.

[pocket-rocket]

Wouldn't a bad cat make it dog out over 3k rpms as well?