Have you checked out your suspension components?
Check your tie rod ends. They are cheap to replace and can cause exactly this kind of vibration.
Have you considered you may have a wheel force variation problem with your tires?
If you do, the Hunter GSP9700 is the only machine that can balance your tires. It will also tell you if they can't be balanced.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".