In the past, I have had to tape my multimeter to the windsheild to monitor backprobed connections. You may want to try that before replacing the PCM. It is possible that a ground is dropping out. First back probe the +5V reference wire with the DMM ground connected to the battery negative post. The voltage should not waiver. Next, test the ground circuit to the PCM by back probing the ground wire at the TPS with the DMM positive lead connected to the battery positive post.

Heck, for cheaper than that, you can get a loaner PCM from PCMforLess.com with a tune and just send in your current PCM as a core. Cost for the tuned PCM is $175 plus the $125 refundable core charge. They will program your PCM to the options your vehicle has based on your VIN. There is the possibility of having to have a CASE learn done, but maybe not.