I would speculate that you either have a very worn out front flex disc and / or broken differential mounts.
In the case of a very worn out flex disk, you want to get this looked at immediately.
If it breaks when you are on the road, you will do serious damage to the underside of your car, as it will take out your center support bearing and the drive shaft will bang against the drive shaft tunnel. Your airbag, if you have one, will also explode as the sensor for the airbag is right above the drive shaft.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".