It is hard to describe, but a lot of times I am starting off or trying to idle in a parking lot and it starts bucking. It is not engine related I don't think. Sitting in neutral it idles smooth even as I increase increase RPM's. Best way for someone to duplicate it is to drive your vehicle and tap the gas on and off. Make you jeep jerk and that is what mine is doing. In my head I feel like has something to do with having such a high ratio rear.