Transmission problem? on 1999 Mercedes-Benz E430

Sport model with 120,000 miles. Car has never been a problem and runs great. Except...we have a vibration at red lights while in gear. No vibration if in netral or park. Engine and transmission mounts replaced but no less vibration. Not sure what to check/repair next. Any suggestions on possible problems? Thank you

Asked by for the 1999 Mercedes-Benz E430