As usual, I'm guessing a little and working from 20-year-old memories, but in general, your engine control computer should go 'open loop' when any critical sensor fails. It has programming that will allow you to 'limp home', err'ing to the side of rich to prevent overheating.

Therefore, yes, the engine should start and run with no AMM, but it probably may not develop enough power to run very fast. If your engine runs BETTER with the AMM disconnected, that would indicate a bad AMM. If the engine runs WORSE with the AMM disconnected, your AMM is not out of suspicion, but it is no longer the prime suspect.

As you no-doubt know, the self-diagnostics on cars in 75-85 model years were notoriously unreliable at pointing out the actual failure. They are still far from perfect.

I once bought a new AMM for my '91 based on a self-diagnostic computer code. Turned out that the AMM was not the problem. What was worse, I had turned in my old one for the core deposit, so I don't have it in case the new one ever fails. If you knew how cheap I am, you'd understand why it brings tears to my eyes just thinking about it. ;)