I had a similair problem with mine. It turned out to the clips that hold the fuel injectors were broken. This caused the x to sudder real hard at low RPM's, until enough fuel gets to the motor. One clue would be really bad milage. I get 13 city 15 highway and my milage dropped to 8-9 all the time.
when ever i go to car wash and i never get the underbody wash my x runs like crap for about 20 minutes. feels like it has a miss and is sluggish. i checked the air filter and it is always dry. dealer said if coil packs get wet will run bad until they dry out.