Your EGR problem is likely a blocked "hot inlet pipe" to the intake manifold.
It is a well-documented problem on these M104 engines.
Search the archives and you'll see tons of posts on the problem.
The blockage is where the pipe meets the intake manifold.
You can either ream out the pipe, or replace it.
Stevebfl (Steve Brotherton) also points out the problem with pictures in the DIY link at the top of the homepage under the article Evaluating Electronic Engine Controls, or something like that.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".