Pulled fault codes:

P0507 - Idle control system -RPM higher than expected

P1580


And then replaced actuator... which solved the problem.


BTW, removing the air intake duct and peering directly into the throat of the actuator revealed that the actuator's butterfly plate was open approx. 45 deg., instead of being closed - a clear indication that the problem was actuator-related.

Inspection of the failed unit following its removal revealed that the butterfly plate was no longer operating smoothly through its arc of travel and was failing to return to its baseline idle position.... a crunchy, jerky sensation could be felt when manually cycling the plate. The difference was obvious when compared to the new actuator.