Mine shakes like heck while idling! My problem with the motor is slowing it down to an idle! It doesn't want to come back into a idle when landing, I normally cut the throttle to idle as I'm just turning onto the base leg and finally just before touch down it slows to a decent idle? It has done this since it was new? I've have the low end as rich as I can and still have it run. Oh well, I took it out of my Ultimate and put in a 3W so now I don't have to worry about it!