I don't think it's actually LIMP. OP is just using that term because he doesn't know what it's doing.
The ~2 minute thing sounds like what I was dealing with in the beginning and you'd helped me with. STFT's would be fine at idle for a bit. Then they've methodically lean out. Then back to normal. Then lean out slowly. You'd said the MTF was off and it was using the failed MAF table.
I corrected the MTF and all was well.
The leaning would fit with the O2 code I'd think.
But if he'd actually pull a log and send it your way we'd know for sure. I'm just not sure why he hasn't, yet complains daily.
Don't "think outside the box".
There is no box.
Do it correct, or do it twice.