I had a p0101 that felt like a loss of power under load. by that I mean the code was there after this event. I cleaned the MAF with CRC cleaner, re-installed. It then read what seemed quite low (4.5g/s). Before this, it was reading between 8.5 - 11.5 at low/high (cold) idle. MAP reading is within range, ~75kpa @ 8300 ft.
I'm trying cleaning the MAF again just to ensure something didn't get missed when i blasted it.
also in the meantime, i checked the leads. the ground seems good (< .05ohm), the pos lead had full voltage (+/- .05 V relative to battery) however it did have around 100Ohm resistance.. not sure if that could be part of the problem.
At this point, from what i can tell, it seems like the next possible things to check / could be the problem are:
1. Replace the MAF, it's bad
2. Exhaust or intake restriction leading to actual low flow
3. Vacuum leak, less air through MAF but coming from elsewhere
4. Grounds -- seems like MAF is ok, but maybe PCM ground is no good leading to bad reading?
my thoughts are : #1 is last resort hopefully, #2 seems unlikely as it was reading more before the cleaning.. but maybe that was incorrect? #3 - possible, but i think same, wouldn't this mean the MAF reading wouldn't have really changed and problem persists? also, no blower noise under the dash when accelerating. #4 definitely possible, but i'd think i'd be getting other error codes as well
Documenting here for science and to see if anyone has

Edit: at one point during a long drive when the P0101 came back, there was a pending P0131 (o2 low voltage B1S1) that popped up pending, but then went away. perhaps could be related