Need help. TPS codes

[rwolf9653]

Hello all. I have a 2003 Chevy suburban 2500 6.0 liter with 160k. For the past several months I have been unsuccessfully chasing TPS voltage codes 2135, 1516, 0220, and maybe some others a time or two but these are the major reoccurring ones. Here is what I have done so far in attempt to fix the problem:

1. Replace TPS wiring harness at throttle body. Cut existing harness about 2 inches from clip which I later learned may not have been far enough.
Drove for about 50 miles before light and reduced engine power.
2. Replaced TPS at throttle body. Rock Auto Dorman brand unit.
Drove about 2 days before the light and reduced power returned.
3. Read that aftermarket parts aren't right, replaced whole throttle body and TPS with GM parts( only sold as one unit.)
4. Ran jumper wire on the yellow power wire to the throttle body sensor from about 12" back to the harness. Some say the break could be as much as 6" away from the harness so I figured this would carry the voltage either way.
Made it almost 500 miles before an highly disappointing failure again.
5. Replace pedal throttle position sensor. Why not? It is the only sensor left. Shooting in the dark now. Tested harness and found no problems.
6. Cleaned ground at firewall that runs to the back of the block. Works on old trucks, right?
Drove 150 miles and got rejected again this morning.

Seriously frustrated so any suggestions you have are appreciated. My wife has lost faith in the reliability of this vehicle now and is on me to get rid of it, and honestly if this doesn't get figured out soon I am leaning her way. Going into limp mode on the highway with kids in the car is just dangerous and GM should have thought that through a little more.

[clinebarger]

Clean both Grounds (G103 & G104) at the rear of the engine, Pulling the Intake makes it a lot easier.

[rwolf9653]

I will give it a try. Thanks.