'94 940 turbo 270,000 km

Two days ago it stumbled badly for a few seconds, then OK. Just enough to get me worried.

Yesterday on a 50 km trip running several errands, after one stop, the car would barely pull above first gear. Lots of stumbling, and if I kept on the gas, would stall.
Back off the gas and it would pull, making me think it is a fuel problem. The tank was full.
Restarted just fine and idle was fine, but no guts. No codes or check engine light. Eventually I unplugged the AMM and behold, it ran. So I continued my errands. After about 5 km, symptoms came back and it died again. This time I reconnected the AMM and everything back to normal. I didn't reset the codes, just drove home about 20 km no problems.


Fuel injection relay was resoldered last year, and seems OK.
Today I removed and cleaned the AMM, the connector looks corrosion free.
Also pulled and resoldered the radio supression relay - found a couple of solder cracks there.
No gas smell at FPR, no gas smell at exhaust or outside the car.

Do AMMs fail slowly/intermittently? What else should I check?