The timing belt has not jumped or broken. The engine runs perfectly. It is about due for a timing belt which is next on my list if I can figure this problem out first.

Rabbit: You are correct, the codes reset because those 2 sensors are not getting the required 5v. I did check and re-ground the ECU grounds to make sure they were getting a good connection. It did not solve anything.

Both the TPS and the Evap sensors are only reading 0.23v from the 5v supply wire.

I can actually get rid of the TPS code if I hold the gas pedal down the entire time (when erasing the code). But as soon as I let go it sets that code again.

According to my service manuals, the TCM should have 12v on the serial connections to the ECM. These are the ones reading only 2.6v. I've checked the resistance on all of these wires and everything checks out fine.

Is there a ground or a supply wire somewhere before the TCM? I don't know what to check next. The service manual doesn't give me any more options to check. It just says replace the TCM and ECM, which I've already tried.