Truck Forums - 8.1 L Check Engine + Reduce Power light

Ok...everyone. Here's one that's stumping me. Before, I describe, know that I've already thrown a good amount money in repairs and new parts at this problem.
So, my issue is the truck running fine and out of nowhere lights up the dashboard with both the 'Check Engine' plus 'Reduce Power' lights. And, does go into a reduced power mode. Along with running real rough.
Initially, it was giving Throttle Body type error codes. Which had ne change out the TPS three different times. And, the actual Throttle Body twice. Plus, I changed out the Pig Tail part of the wiring, as well.
No success!
Then, after some research, I started replacing air intake parts.Air Filter, MAF Sensor.
Still no succes!
The interesting thing about this problem is that it seems to happen much more frequently during cold weather. Like 40s and below???
Anyway, looking forward to suggestions !

Socal8

'02, 2500HD, 8.1L, 4x4, Allison, crew cab, LS