Few back ground notes. I purchased a 1990 4Runner Automatic 4x4 with typical V6 headgasket issues. Turned out to need an rebuild/new motor. I threw in a long block and am now trying to get the remaining kinks out of it.

Here are the symptoms:

1. Once it warms up and the idle drops from the initial high speed warm up, it wanders up/down and sputters once in a while.

2. The Check engine light is not on, however if I pull the codes I get a Code 51 or TPS code. I have been unable to clear this code.

3. It will run/ drive great, then randomly not down shift. When it does this the O/D light blinks. If I stop the vehicle and let the rpm's drop to idle, the O/D light turns off and tranny will function properly. Again this is not consistent and occurs randomly.

4. The truck is a 3.0l Auto, with a 4" suspension lift and 33x12.5 tires. The best fuel mileage I am getting is 13mpg highway with ECT switch in econ mode. I know the 3.0 is not a great gas saver and the 33's do not help, but I expected better mileage than a half ton small block.

Any ideas on these issues?

 

sounds like maybe is a bad tps or its out of adjustment

 

Do you think the TPS being out of adjustment/bad could affect the transmission shifting? Or is this just another problem?

 

well i'd start with that. Transmission works with the motor so if the motor has issues.. it could link over.

 

the TPS tell the computer the throttle position, the kick down works off of throttle position. theirs your link. adjust the TPS and see if it goes away.