Have a 2007 Cadillac STS4 with 3.6 litre V6 engine. Out of the blue the car started vibrating at idle. It's as if the engine is sitting solid on the frame. I've replaced the throttle body, mass air flow sensor, throttle position sensor and gas pedal with new sensor and nothing has helped with the vibration. If anyone has any clues please reply. Other than vibration at idle car runs fine. Thanks in advance!