I've been following your dilemma over the past number of days. Sorry to hear of your continuing troubles.

It's recommended to not remove the plug from the AMM with the car running! I have seen posts on this board that emphasize this to no end. There's a chance that you've fried your AMM.

With that in mind, one of the tests to see if the AMM is bad is to run with it connected and then run with it disconnected. When disconnected it will go in Limp mode and if the AMM is bad it should idle normally. It does sound like it's something more than the AMM.

My guesses:
1) How is the air filter? Have you confirmed that there are no obstructions in the air intake line (from front of car all the way to throttle body)? If the car has been sitting there may be a rodent nest blocking your air flow.

2) Has the throttle body been cleaned?

3) How is your throttle position switch? Adjusted properly? I think your car has the LH2.2 engine mgmt system. If so, the switch should "click" just at the point where the throttle plate is coming off of idle. Sensor is on the side of the throttle body.

4) Injectors flowing properly? The injectors are easy to pull out of the intake manifold, you might want to have a set of injector o-rings on hand just in case the ones on there are in bad shape. I've had a set of injectors cleaned for like $11 a piece, they flow like new now. Had them done by www.cruzinperformance.com. It's a one man show, great service, and often times will push aside other work to get yours back to you ASAP. Paid $65 for all four with shipping there and back to the North East. They come back with new seals (a seal kit from FCP is $2 or $3 alone) and if one of yours isn't flowing up to snuff, he'll replace it with another used one that has decent flow (if he has them in stock.)

Some questions for you...
How was the car running before the blown head gasket?
How did the head gasket blow?
How many miles on the car?

Good luck,
Bean
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'80 242GT 92k, '94 945T 123k