Some here might remember about a year ago when I had an episode where the car nearly wouldn't stop at a stop sign, and then after stopping I realized the engine was fighting me, idling at almost 2000 RPM.
Then after taking off again, the tranny hesitated on the 1-2 upshift, hanging too long and then shifting harshly. After a few miles, the CEL came on. A little later that evening, the problem went away, and after a restart, the CEL was off once again.
We all speculated, and I was too lazy to read the code and see what happened, and it's been fine until two days ago. Then the same thing happened. I noticed that by shutting the motor off and restarting, or unplugging the TPS and plugging it back in while idling, the idle would settle down until the throttle was opened again.
So today I put a new TPS on, and after a short drive (6-8 miles) to re-learn proper idle strategy, the CEL went off, and all is normal again.
Apparently without a proper reading of throttle position, the ECM can't properly signal the tranny solenoids to upshift, having no way to reference the demand being placed on the motor.
Just thought I'd post it, and try to include all the search words that might help someone with the same problem. Wonder how many tranny shops have sold a "rebuild" based on this malfunction
