Lincoln Vibration

I have a 2001 Lincoln Town Car that has an intermittent vibration that can be felt when seating in the car and you move the gear shift lever to D for drive. The car has 141,000 miles. It is an automatic transmission. The vibration cannot be felt when touching the steering wheel. What could be causing the vibration?

Possibly a worn transmission mount

Thank you for the comment. The transmission mount has been replaced and it still vibrates.

Are you sure you don’t have any kind of misfire?