Major Idling and Running issues

Okay this is gonna be a long post! Bear with me.

I bought a 09 G8 GT with a failed lifter. Decided to buy and cam swap it with All supporting mods.
Cam: BTR stage 2 LS3 cam and kk supporting mods.
Custom CAI
Stall
All the goodies.
Had the car tuned. Car ran perfect for about a month and then things went south.
The car started to develop a weird and random cam surge/stalling on start up, reverse, and going from drive to park, the rpm’s would bounce up and down till it eventually stalled. We did a throttle body relearn on the OEM LS2 Throttle body. That fixed the issue for another month. Then all the same issues came back. So we thought it was a tuning issue, it’s wasn’t. Nothing in the tune file looked off. Replaced with a known working LS2 throttle body. Performed a relearn on the car. It drove perfect for a month. Then all the issues have come back and is requiring a relearn almost every other week.

We’ve checked the MAF and it’s working perfectly.
MAP sensor is working as it should.
When the car is hooked up to a scanner, everything reads as it should. No irregularities.
We are thinking possibly an issue with a wire somewhere, checked all the wiring.
No vacuum leaks.(Created one and confirmed)
New Battery.
I am completely stumped at would be causing this. Any input or advice to go off of would be wonderful.