The fact it detects the error without even starting the engine indicates that the ECM is not seeing a valid input from the MAF. Seconded by the lack of MAF data on your scan tool. IMHO, that means one of the following exists;
Bad MAF- ruled out
Bad wiring FROM the MAF to the ECM (the reading of 5 volts at this input is not definitive that the wiring is OK)
Bad ECM input circuitry
If you ohm out the connection from the MAF to the ECM connector pin and it reads OK, I bet you have a dead ECM input and it needs to be fixed/replaced.
BTW- getting snippy isn’t helping win any people over to helping you. If YOU read what you wrote, lots of the detail in your last post is not in any of the prior posts. Typically, you reap what you sow…