Laniohan4

I have a 1999 Chevy suburban 7.4L it has 187,000miles.
It has intermittent shifting problems some days it runs fine most days shifts really hard in 1,2,3 but at highway speeds it is fine. It throws a dtc p0712 transmission temperature sensor.I took it to a transmission shop they replaced the internal harness. Got it back and it did the same thing and threw the same code. Took it back he said the transfer case seal needed fixed. So he replaced the seal. Got it back and it did the same thing and throws the same code. So I took it back and he said there is a short in the vcm/pcm and it needs replaced. I ordered it and put it in myself. After all this it is still throwing the same code and shifting hard intermittently. Same problem!
Someone help please!!!