I've been trying to get to the bottom of some nasty shifting and torque converter lock-up issues my truck has been doing.
Its a 5.8L with the 4speed with O/D (5speed auto)
The speedo was out of commission for sometime due to the tone ring in the rear end. I've since fixed that and it seemed to take care of most of the issues.
But now when i run WOT the tranny doesnt let the motor wind out.
At WOT it shifts out of first at like 3500rpm and so on through out the gears.
And wont downshift at all
Any thoughts as to what could be the problem.
It just threw a P0122 code (TP Sensor A Circuit Low Input)
Could it be a bad TPS?
Thanks for any help.

 

You do not have a 5-speed automatic transmission in that truck unless someone went to a lot of trouble to install one.

As far as your symptoms and trouble code go, yes a bad TPS or wiring issue can cause them. Invest in a cheap meter to measure the TPS output before throwing any parts at it.

Use this for reference: Fuel Injection Technical Library » Throttle Position Sensor (TPS)