Hello again Everyone. I guess this is my week for questions.
I have codes P0121 and P0121. Both refer to a week signal from the TPS. I have replaced the TPS twice and I still get the same code. So I believe that the signal wire is broken or frayed. I've tested the 5v and ground lines and the are Both fine. Reed 5v with the key in the on position. I was also able to read the resistance change from the each of the outer pins on all 3 TPS to the center pin. So that points me to signal wire. But without removing the whole harness from the PCM, I can not test that wire and even if I do, if there is one good strand of wire, then it will read as 0 ohms on the multimeter. So how should, do I test this wire to find the brake? There is only about 4" of actual exposed wire before it goes into the Harness leading to the PCM.
Symptom: when driving in a parking lot or Very heave traffic, if I Tap the gas and then release it, the idle drops to about 300 RPMs then pops back up to 700 to 900 RPMs. Sometimes, if I tap it light enough, the motor shuts off. There is Also a sulfur smell But only when I am Hard on the gas. I need new ideas!

Thanks

 

I looked the two codes up in the shop book. An interesting note I saw on code P0121 was this:
PM me your e-mail address, I can send you the actual GM shop manual data for those codes.