Help a homie out.

I am about at the wits end gentlemen.

Finally got my 80e swap done. Got the "correct" segment for my PCM. Because my PCM apparently has se kind of off brand OS ID.

Now to the issue at hand. Driving down the street logging the truck. It varies on the time it takes. But it will suddenly jump into reduced engine power and die. Isn't throwing a code. Most codes are turned off in the truck. Can a code that's turned off still cause truck to die? It is random on time. It doesn't seem to ever do it at idle. I've sat in the yard and have had it sit for 20 minutes waiting for if to happen. Only when going down the road it seems.
The log is literally perfect. Afr is 14.6. It's normally advancing about 40 or so degrees if I'm cruising at 55 when it happens. O2s reading correct. And literally with zero warning, knock, anything it's like the log stops. And is dead soon after. Can the PCM be losing its connection? The wiring I have checked and double checked. I have a tune in I have yet to try that literally has damn near every code enabled to see if I can catch it screwing up. When it goes into reduced before it goes dead not even o2s are reading.
Any ideas? Anyone seen this?
Also once dead if won't crank again. Fuel pumps seems to TRY to kick on but something isn't letting them get/keep power. Turn key and they come up to say 40psi but don't stay on. Relays are all clicking. Starter can spin till battery dies and will never turn over.

What codes are you getting, that you're clearing.

Already told you with this, but when I was fighting mine, shutting the codes off didn't help. It'd still go into REP, it just wouldn't tell me. Turn the damn codes on so it'll give you something to chase, instead of just a ghost.

The tune I have loaded now has literally every code turned on. But I haven't taken it out for a spin yet. I'll have time again Thursday for that.
Codes it's always giving me whether they are turned off are not are MAF codes ( being there isn't one at all ) and for some reason a evaporate system low pressure. Which is also gone.

Gotta have all the rep codes on so they will point u in the right direction.