I have a 89 Firebird MPFI 2.8L Automatic w/ OD, thats mostly stock (CAI built by me, TB coolant bypass, cat gutted after it plugged).
I've had the car for coming up on two years now with virtually no issues. One thing I do remember is when I first got the car it seemed to me like the transmission was bad. (I am very far from a tranny expert, they frighten me ) It never seemed to shift right. When I pressed the gas, It would seem to downshift before it upshifted, and sometimes would seem to upshift for no apparent reason (steady pedal pressure) while cruising at 45-50.

One of the first things I did to this car was put a different radio and as part of that I spent some time under the steering wheel. While I was down there nigh on two years ago I checked out the Stop light switch and all the fuses, and I saw another plastic gadget right next to the stop light switch. I unplugged the vacuum line to see exactly what it was, and the whole durned thing fell apart. I plugged the line (not exactly knowing what it was) and took the remnants out, including the "power" connector. I didn't think anything of it, and went on to have my tranny fluid/filter changed that day.

I thought the tranny fluid change was what fixed my tranny shifting/driveability issue, because after that, I noticed my tranny never randomly shifted.

The other day I found my cars twin at the junkyard and got the connector that fell apart. To my surprise when I hooked everything back up, I found I had the same issue that I had before! It would bog down at cruising when I pressed the gas, before upshifting, and sometimes upshift or downshift on its own.

I did some research and found the vacuum line was for my cruise to tell it when to shut off, and the power connector was just a switch that de-energizes the TCC solenoid circuit!

Is the behavior noted above normal for a TCC, or am I just picky about how my car shifts? Could I just need to adjust my TV cable?

On a related topic (perhaps this is caused by not running the TCC for two years) my car no longer moves in the morning when I put it in OD. I have to start in D, (takes about 5 seconds) and then when I hit about 35, I can switch to OD, and it works fine. It takes a good bit of driving before it consistently starts moving in OD from being shut off, but it does.

Any thoughts?

 

I will put my .02 cents on the last perigraph, your trans is about to die. Typical activity for an GM over drive tranny to do before it dies. Thats my expierence, Thats my opinion, sorry to give bad news.