As you may have seen repeated by Larry Bible and other forum members in the archives, this sounds like a job for the Hunter GSP 9700 wheel balancer. This machine can detect wheel/tire problems that normal tire balancers cannot, and fix them.
Go to http://www.gsp9700.com
to find a shop near you that uses one of these machines.
'01 E430, Sport 72,000 mi
'98 C280, 126,500 mi