AMM=Air Mass Meter...what you are calling MAF Mass Air Flow Sensor (a generic term that covers a couple of different air flow/volume/mass sensor types). It is very, very odd that it will start and run with the AMM connected and not run with it disconnected. It should run in Limp Home mode with it disconnect (aka badly and very rich). the wiring terminates at the ECU as it is just measuring the air coming into the motor.

From the 700/900 FAQ:

https://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm#LH24FuelInjectionFault

"Wiring break between FI terminal 8 and AMM #4" If I remember correctly this can be a false flag unless accompanied by a 2-3-1 or 2-3-2 but that is purely from memory. Are you sure you do not have a second stored code? This coupled with the no-start with the AMM disconnected has me puzzled unless there is a massive vac leak like a disconnected or split brake booster line which would likely trim one of the other two codes.

FYI, every time you disconnect that battery cable to clear codes instead of using the ODB box, you loose an adaptive trim information that has been learned by the ECU. My understanding is that most is restored withing about 15-20 miles of driving. Not a bad thing in the grand scheme of things but you may notice some idling differences including return to idle from cruising.