My engine developed the same problem a while ago.
My mechanic replaced the mass air sensor, and it didn't fix the problem.
My mechanic then replaced the throttle actuator (you car doesn't have a throttle actuator. You have an idle control valve). It didn't fix the problem
The mechanic gave up and told me to take it to the dealer.
They immediately diagnosed the problem as a leak at the intake manifold gasket. $400 later, the car was fixed.
Needless to say, I now have a new mechanic.
