someotherguy
+1y
Easy enough to take the screws out of it and bungee it to something in a way that it's not grounded. Don't think that would do it but once you start dicking with grounds, it's possible to cause problems. It's too easy for people to think more grounds = good and in a very simple sense that's basically correct, but you get the wiring scheme too screwed up and you end up with ground loops and all kinds of freaky behavior. I say try to get the setup as close as possible to how stock would have it, I know the truck is modded and that's not literally possible but you can make it at least electrically similar and see if that helps.
Are you 100% sure you didn't damage the PCM sticking screws into it? Did you drill/tap or use some existing holes, and if so, were they blind?
Richard