I had been having this problem, and had been searching and reading all that I could. A fellow here at DTR suggested replacing the TPS, so that's what I did. It is behaving much better, now. The old TPS was pretty worn down where the throttle shaft goes into the sensor. Now, it shifts into O/D and then lock up, and doesn't hunt or shift in and out.
The other good news- I found the TPS at Autozone for $126.00. The other two prices I found were $167 and $202, so this is a significant price break.

 

Glad to hear it fixed it.. Another potential problem spot is the brake switch on the brake pedal lever. It sometimes pops out of its holder and starts to do weird things..

 

I put a Potentiometer in place of the TPS on mine. Cost me $3.17 and is adjustable to bring O/D in exactly where you want it. It hasnt dropped out of O/D once since i did that.

Just another option for fixing it.

Eric

 

I had checked the brake switch, alternator cable, battery cables and ground, and had settled, after being given the advice, on the TPS. It was expensive, but not as bad as it could have been. I am very pleased in the result, as well as the simple fix.

 

i"m new to this forum and want to thank you all.....i installed the pot inplace of the tps.i wish i knew about this befor my trip from ny to ks last year .... we put 3400 miles on and the tc would unlock at random times . it has not unlocked once since i installed the pot ......