I have been looking over the forums and I知 sure the right answers are out there but have not found them yet. The problem is the automatic transmission on my 96 is not shifting correctly. Its behavior is not only wrong but very inconsistent. It comes in and out of lock up, shifts up and down at will with no regard for how fast you are going or the RPM the engine is at. When in D it may or may not shift up, but definitely at the most inopportune time it will shift down. The guy that got to drive behind me in the 45mph zone with me going a cool 30 with the tach pegged I知 sure thought of me as a friend for life. It has the same behavior when in 3rd and has shifted itself out of 3rd to 2nd once or twice. I have cleaned all my battery terminals and cracked open the TPS for a good scrubbing as well. I知 at a loss, any ideas or advice would be greatly appreciated and welcome. Just for the extra info this is all happening without towing, under normal conditions. Transmission is running slightly hotter than I知 use to seeing and the fluid level is a bit on the high side but not over the upper limit on the stick. Fluid and filter have both been replaced in the last year however it did not get flushed. Trany has about 175k on it, I think, I bought the truck used so who really knows for sure.

 

The TPS along with engine speed tells the transmission when to shift and unlock. Id check / adjust / clean or replace the tps, search for posts that give info on shielding the TPS wiring and reducing ground noise. electrical noise in the system gets coupled to the tps wiring and gives abnormal voltages. There was a post somewhere here or on DTT's forum that talked about this.
The other things to look at are the OD temp sensor which is on the drivers side of the transmission pan. You can replace that without draining fluid if youre fast and its only 20 bucks.
A transmission temp gauge will also tell you if that dropping out of OD is temperature related or not.

 

BD, very ammusing post! I have the same problem with my 96' too. Did you ever figure out the problem?