Do not expect miracles on this one, but you may find the MAF starts to report after unplugging and reconnecting, bad connection or broken wire.
But a this point the MAF is effectively disconnected because there are no MAF readings being picked up by the DME.
Also note the Freeze Frame data had Misfires for Cyl #4 & #6. These just so happen to be the 2 spark plugs that are not all carboned up. #4 & #6 appear Lean??
Rarely do ignition coils act up on cold start or idle, but they could. I would also think if #4 & #6 coil were having problems these plugs would appear to be a bit wet with fuel.
The STFT for Bank #1, Cylinder 1-3 is way Negative, trying to remove fuel due to a Rich condition which I agree with due to the spark plugs and the lack of a MAF reading.
The STFT for Bank #2, Cylinder 4-6 is way Positive, it is actually Maxed out at +30% at highway speeds. This tells me there is a Lean condition for Bank#2 which the spark plugs and STFT seems to agree with.
I am thinking you have some sort of crankcase air leak or a problem with a CCV hose as a guess??
I think it is time to think about Smoke testing for air leaks in the crankcase and/or intake path.
In case I did not link this previously, here is a simple Smoke Test below. The fluid transfer pump is about $10 and most Auto Parts stores and maybe even Walmart may carry it.
I am starting to think you have 3 very distinct problems.
1. Engine running too cool, probably a soft thermostat. I really do not think these engines are supposed to run a 175F/79C on the highway. I expect 205F/96C range, maybe just slightly higher. This may be due to no MAF signal and the DME commanding the thermostat heater on? You may try unplugging the thermostat heater connection and see what happens to the temperature. If it operates in the range I expect it to, then the thermostat is not actually bad but something may be commanding the thermostat heater on. This also assumes this engine has the electrically controlled thermostat which I believe it has.
2. No MAF reading. Not sure what to guess at here. Bad MAF or bad connections. But check fuses first.
3. Some sort of vacuum leak that is not in the main intake path, probably CCV or crackcase would be my first guess.
https://www.youtube.com/watch?v=AsgB9eBl58I