I had problems with tranny shifting into overdrive - i followedinstructions on here and cleaned the tps- also check voltage- it was fine- 5.0v @ reference1.5v @ an idle, 4.0 volts @ full throtle it shifts better into overdrive now but its hunting for gears 1-3???????

 

hopefully you got it fixed, but if not, try replacing the brushes in your alternator. This was happening on my '02 and thats what is ended up doing.Apparently there is static ''noise'' that originates here and it affects shifting.

 

What year is your truck??? I believe the tps only controls the 3-4shift and tc lockup.