Thread: transmission slipping or something else?

I got a 2002 gt with 120k miles on it. Just recently ive noticed that when I punch it and the car downshifts and is now at like 4k+ rpms it isnt accelerating? It's really weird, it's doesn't seem like the tranny is slipping because it doesn't rev even higher. It just seems almost stalled. If I punch it from a stop it pulls like it should untill I hit that 4k rpm mark then it seems to lose power? Does this sound like a transmission problem or something else? I just recently replaced the plugs and wires so I don't imagine its that. I did a little research and someone said they had similar problems and it ended up being the number 5 and 3 fuel injectors were bad. Could that be the problem? The car had been driven mostly on the highway its entire life. The transmission otherwise shifts and operates fine. There are no codes. I also (should be unrelated) replaced the thermostat because it was staying stuck open and a code popped up.

Would love any input thanks guys !

Oh and I checked the tranny fluid and it looked normal. I'm starting to think more that its a fuel issue?

any ideas would be greatly appreciated !

So it sounds like a clogged cat? It only has 120k miles on it or do they clog that quickly? Also which cat should I get, aftermarket or oem?

I have 126k miles to be exact. I don't suppose GM will honor the l36 cat warrant because im 6k miles over huh? BS ! which cat should I buy? I have no other mods. I don't exactly want to spend a fortune !

Thanks a ton guys. My cat must of definitely been plugged ! I replaced the cat with a direct fit magnaflow and my grand prix has never run so good. I can't believe what a difference it made. Thanks especially to gtp01 who has helped me several times now.

i have a similar problem. my magnaflow cat and cat-back system is in the mail.
hopefully i'll have these installed by next week