Search for the "RenX files" thread and if you will go through all ten pages you will be a Renix TPS high idle and transmission TPS issue expert. It has a few links IIRC to some sites with photos to.
If you are testing the TPS properly, probes in the right places, have a working ground on the TPS side where you are testing it and if the TPS is installed correctly, then your test results indicate a TPS internal short of sorts, or a constant output voltage from the TPS, which means it IS TOAST, defective, real junk, time to replace it.
Also a fixed volatge on the output side of the TPS that is not changing as you move the throttle (or move the TPS at the throttle body) and if measurement is on the transmission side of the TPS (Square connector) then that would be the cause for transmission to stay in first gear. So that sounds like confirmation that your TPS is shot.
TPS is !!!1.
I made some conditional statements above, because if the the ground connection is bad on the TPS to wiring harness connection that could cause the same problem.
5.0 volts on the ECU is normal. More than that is maybe OK, but not normal. Less tha 5.0 volts input means a dirty contact somewhere which can lead to random variable idle speeds if the contact gets better or worse with wiring contact motion.
I would check and make sure the meter is working right, check that the battery is not dying, is the meter digital or analog? Good analog meters must be zeroed manually before use!!!