the car is a 98 monte carlo with a 3.1 in it. it runs fine up to 2500 rpms. it doesn't matter if you put it in drive or park, it sputters or misses at 2500 rpms. you can accelerate extremely slow and drive up to 60 mph and it drives fine. if you accelerate fast or drive faster than 60 mph it starts cutting out.

it has anew fuel pump and fuel filter. i took the ignition module to O'Reiley's and had it tested and it tested ok. i checked the fuel pressure with the new fuel pump and filter and it checked out good also. i checked the self diagnostic system and it has no codes in it. the fuses are good also. it has new plugs and wires on it.i hope someone out there can help me find the problem out on this.

 

 

I posted this in Jasons thread but i'll do the same for you. I had a very similar problem as you. At times when i accelerated, it won't go above 3000rpm, and every time it hit 3000 it would stutter and my car would start to shake. I couldn't figure out what it was, throwing no codes, nothing. Finally yesterday I was at a set of lights, and my car was idling at 800-900, bouncing back and forth, shaking the car. Shifted to drive, nothing, shifted to neutral, no change, finally to park and it stalled. Started again, ran for like a second, stalled. Waited like 2 minutes while the light was red, started once it was green, was able to get it going, but this time wouldn't go above 1000 rpm. Moved out of the intersection, at a very slow pace, and luckily it stalled once i was to the side. checked under neath the hood, couldn't see anything was wrong. Double checked my wires were on properly, started the engine again, and it ran just fine. Got it to my mechanics, had him check it over. He replaced on of my wires(for free thankfully), and its been running fine every since. I butt loads of power again.

Now my problem was intermitten, so if yours is a constant you might wanna try the cat. If you have a spare set of wires kicking around, try changing with those and seeing how it runs.

 

I have a similar problem happening with my 2002 Monte Carlo SS (3.8) Buick SFI . In the driveway it starts and runs fine . When you let it warm up and try to rev it up , it will not exceed 3000 rpm's . I have a code popping up of miss fires , and EGR out of range . I have replaced the EGR , coil packs , plugs , wires , tested the ignition control module underneath the coil packs , replaced the air filter , and tested the alternator to see if maybe the computer wasn't getting enough power fed back from the diode's . Has any of you had the same miss fortune of a very nice car falling on it's face .

 

This is a 7+ year old thread that you brought back from the dead.

Anyways, have you checked the cat or O2 sensors?

 

Sounds like you have done everything that is possible, I am thinking that the Catalytic Converter may be plugged that happened to me on a few cars and it acted similar to what you have described. One other thing I discovered on my sons 96 Monte was a Vacuum line was off the connection, after I reconnected it, everything worked again with no more issues.
You may have a leak in a Vacuum line also. Sometimes the old rubber and plastic fittings crack.
Hope it gets fixed.