I cleared out the tube on my 94 E320 this spring and the CEL has not turned on since.

The tube needs to be cleared out at the intake manifold. Follow the pipe from the EGR valve to the intake. It goes behind the head, in between the head and the firewall, where you wont see it. It comes back into view where it's fastened to the oil filter housing, then runs to where it mates to the intake. I was able to get the two 10MM (i think) bolts off with a couple of extensions and a universal. I then pulled the tube away from the intake and up (or down) a little. The afflicted, clogged portion is only about a 1/4 inch in and theres some junk in the intake hole, was careful to get it out without pushing it in. For tube and hole, I used a thick round wound guitar string.

Its one of those procedures you've just got to figure out by doing it. A little common sense and a light touch, you should not have any problems.

Good luck.