My original EGR seemed to develop quite a leak, above the gasket, because the tops of the mounting bolts get soot covered, as well as anything within a few inches, like the side of the valve cover. I grabbed the valve off my parts car that showed no signs of soot anywhere near it. Sure enough, I've got soot, same symptoms. Any ideas? I'll snap a photo later, but it seems it comes from the pintles.

No soot after running on the 93? But it soot'* up on your 92? Running rich at idle perhaps?

remember his destroyed 02 sensor???

92 and 93 leaked soot. It was leak free when it was on the 93.