[91civichatch2571]

do you have a modified exhaust? If you do, the backpressure is going to be different, it might backfire or pop occasionally which could cause the motor movement you were talking about. A couple things you might want to check though just to be safe are, timing, maybe have the car hooked up to an osciliscope at a shop, it shows how the engine is running, how strong the cylinders are firing, etc. also, if your motor rocks a lot, you may have a bad motor mount