Ive been trying to figure this out since we got the motor in. We're working on an Evo V, pulled out the motor to work on it, cause the belt broke, we changed the valves, the cam, cam shaft and belt, and everything else was fine. Now we put it back in and test drove it, everythings running fine until you're parked and on idle, the RPM juggles between 700 and 800 every 3 minutes or so, and it sound like it going to die out. We changed out the spark plugs and MAS, and still the same. I did notice some clicking in the motor before the RPM drops though.