2004 Volvo S60 2.4.
Problem: Engine stalls at idle and coast
Symptoms: After at-minimum of an hour of driving, my car will stall at idle or when coasting. The RPM will suddenly drop lower than the normal level (750rpm at a stand still) and putter as if attempting to stay on when I am at a complete stop or simply coasting at speed. If I drop it to fourth, it will rev to about 5000 rpm and level out (at which point I drop it back into drive). No check engine light, and starts right back up after I put it in park.
Ideas: Transmission failing to properly downshift , MAF Sensor dying (although no code), ECM failing.
ruled out: dirty throttle body(cleaned personally)

Any ideas from the community?
(PS. I am a long reader of these forums and greatly appreciate the community input. If this is posted in the wrong place or there is already a thread I over looked, a point in the right direction is much appreciated)

 

did you look into the ETM (electronic throttle mechanism) failure symptoms? tranmission failing to downshift could be caused by a lack of vacuum or confusing sensor signals when the engine stalls out. You could try to reseat the ECM - remove, use electronics cleaner on the contacts, reseat but I'd think you'd get an error code (like a comms error) from the ECM. Also, wondering if it could be a fuel pressure sensor.