Mystery Problem Limp Mode

I've had a very annoying mystery problem with my 86 2+2 automatic thats been driving me nuts. The car constantly goes into limp mode. If I unplug the auto transmission module in the spare tire well the car will run great for one trip. Then if I turn the car off and let it sit, then turn it back on its back in limp mode again. The ecu gives me codes 23 and 31. I'm guessing the code 31 is because my air conditioner doesn't work. I think it must be some kind of electrical problem. My next step is to take multimeter to all the wiring harnesses starting with the two tps connectors.

Here is a list of everything I suspected and replaced:

New MAF sensor
New TPS
New ECU
New Battery
New PCV valve

Along with a ton of other brand new parts that are unrelated.

Any advice would be appreciated, this is my daily driver so its really a pain having it go into limp mode every day, and having to unplug that connector in the back again.
I've tried my best to fix it, I even took it to a local mechanical who couldn't figure out the problem. And when I say limp mode it means it won't rev past the 2200-2500 rpms range.
No matter what I try it still spits out that code 23.