I just changed the Ignition module and coilpacks and its still jarring...I've changed plugs and wires, O2 sensor, fuel filter and probably tackle crank sensor next. Its frustrating when you have No error codes and the car is bucking. It started out just once in a great while but now is frequent. There is a distinct miss while reving in park. I thought it was the module because the other day after starting after 10 sec it stalled and wouldn't crank back. Its the only time its ever done that.. I'm about ready to carry it to the dealer. How do they diagnose it with no error codes??????