2003 Subaru Outback Car stalls at low RPM once warmed up

My 03 Outback H6 (auto) drives perfectly fine until it has heated up to an unknown temperature and then it will stall once the RPMs go under 2000.

It can run forever, perfectly fine in the winter (Canadian winter), but come hot weather and it stalls within 5 minutes on the road (getting progressively worse as the temperature outside gets warmer).

Most of the Engine sensors have been replaced including the 02 sensors. This improved driving performance somewhat but the problem is still there.


When the problem starts the Check Engine Light flickers and the car bucks (very briefly loses power and then lurches), this occurs at speed but it will only stall at a stop, or if we continue to try and run it, at low speeds (under 15mph).

Anyone have any idea what this is? I have heard that the idle control sensor / valve / motor could be defective but would this be at blame if it starts bucking at 75mph (nowhere near idle)?

I tried running the car with an OBDII scanner, no codes show up, and the flicker of the check engine light during bucking is too quick to come up on the scanner. When it stalls the scanner goes dead (no data coming in).