I've had to replace the PCM in my '89. It was clicking up a storm, causing a stumble/ no start symptom that just got worse over time. After finding the wire which caused the pcm death( Transmissiion light blue wire with black stripe was grounding out) I ordered a remanufactured CARDONE pcm through rockauto. They had the automatic and manual transmission numbers backwards, so I didn't have overdrive until I Opened up the originalPCM and found the part numbers, and realized the listing was backwards at CARDONE and RockAuto. They have since fixed the typo.

The installation instructions will say that you must test every sensor for proper resistance before installing the new PCM. I know people who just replaced the PCM just to have it go out again in 2 weeks. Search for the reason of the PCM failure and then replace the unit. I had to trace every single wire leading to or from the PCM from front to back before I found the culprit. It's always the last thing you check. In my case it was the last possible wire I could have checked.

I'd reccomend starting at the wiring for the fuel pump, tranny, O2 sensor, then every engine mounted sensor. Clean every connector with electronics cleaned and apply di-electric grease. Clean the wires themselves with wd40 on a rag. Look for any burnt or discolored insulation.
Good luck

You can send your current PCM to Cardone for a rebuild. They quoted me 2 weeks. This was before I'd figured out the switched model numbers.

 

I hate when that happens. I had a similar problem in getting a new water pump gasket for my mustang GT 5.0L. It turned out that everybody had the part numbers reversed for the water pump and the timing cover gaskets.

 

If this issue could be attributed to a bad overdrive solenoid, how much of a pain is it to replace? I cannot seem to find the procedure in my service manual. I'm just curious because cold weather has made my issue truly critical.

 

Once the temperature started dropping below 40 or so I started heating up the PCM with hair dryer in order to start up the van. Once warm, I could start the van right after a stall or a few minutes time (depending on how much driving I'd been doing). Anyway, when the temp got below 30, the hair dryer method worked just as well to get the van started, but a cold gust of wind while driving would kill the engine very fast. It was extremely dangerous. So, I ordered a new PCM from RockAuto and installed it and I can start the van wherever and whenever I please. One problem solved. Thanks to everyone who helped out.