I agree...clogged EGR tube last year got my 300E to fail for the first time!
After that, drive the s#it out of the car on the highway for a few days prior to retest.
There is some stuff you can buy in a tiny jug called de-carbonizer, that is sort of a "cheat sheet" way to help push along your emission results. Pour it into your tank, then drive around enough to get your cat heated up sufficiently before you get your smog test done.
Mine barely passed after that (didn't get to drive the living hell out of it before the test), but that's all you're gunning for anyway!