Hot Tranny Problems!

I have a 97 GTP and i have been having some problems with my tranny, when temp. of the engine is at its normal the tranny starts to kick when it shifts, as long i have the temp below the normal or when i turn the a/c everything its normal i dont have a problem. I took my car to an automechanic shop to see what the computer diagnose and it check that it was ok. What could be the problem?

I have a 1995 Grand Prix SE with a problem that sounds the same. Mine also only does this when at normal running temp. It sort of jumps back and forth when it shifts especially from 1st to 2nd. Also when I slow down it doesn't downshift correctly either, it vibrates the car really bad at low speed when I take back off. I already replaced the fluid and filter (1 quart lucas) which did not help at all. This makes me believe it is not an internal problem. I am going to replace the vacuum modulator and see what that does. Maybe that would help yours also.

how many miles are on the car? My "x" girlfriend's car did the same thing as the 95 Grand prix...3.1 right? we tried everything. turned out to be spark plugs! weird huh. try that
keith

Mine has 130,000 miles roughly. I don't know how long ago it had a tune up, I just got it like 2 weeks ago. Your X's didn't do that anymore afetr you changed the spark plugs?? That is weird. Maybe it's a fuel type problem....The guy I got the car from said that it started doing that a while back and the mechanic changed the throttle position sensor and that cured it, well now it's back, I think I will try the plugs though, cant hurt plus that would be a cheaper fix. A modulator is $60. Thanks for the advice. Any other opinons would be appreciated.