I have a 95 Z convet with a 4l60e. I put a 52MM BBk throttle body on and a shift kit in my tranny. Well my tranny started shifting all crazy and slipping. Couple tranny shops told me I needed a rebuild on a car that has 68000 on it. Anyways got to looking on alldata and it seems the TPS should be set at .68 v checked mine and it was at .89 v. Got the TPS sensor set back to .68 v and no problems. Just thought I would share.

 

When changing throttle bodies, it is an important step to check the TPS signal afterward. Your post is a good reinforcement of that fact.

 

When I tried a 52MM in mine the same thing happened I also had a TransGo in it. I sent it back and put my 48MM back on. Later I learned that for some, PCM programming is required. There are others on this board that have gone that route and had no problems. Maybe the shift kit has something to do. Our trans's use throttle position for part of its shift point determination.

edit; I just read that you fixed your problem.