Multiple PCM failures

I LS swapped a 2000 S10 to a LM4 from a Trailblazer/SSR. At first I had a battery light that stayed on. A different PCM with an OS that was more compatible with an S10 fixed it.

Since then, I have had 3 PCM's fail. It's always the same scenario. I'm backing out of a parking spot, stop and put it into the D quadrant and it dies. Cranks but won't start. The first time I checked it has no fuel/no spark. They seem to last 6-8 months at a time. I can put the original PCM I bought from CPW back in and it starts and runs fine. I just have the battery light back.

1 PCM was a Flash Masters unit, the other 2 where from used vehicles that I had GM program a specific vehicle to and then I would use HPTuners to swap my tune file over.

Tonight, when I got home. I used a bench harness to read the tune file. I got an error message of "Detect Controller and Get Basic Info Failed" with HPTuners.

My questions for you are:
Has anyone ran into this before?
Where should I start to diagnose this type of failure?