1) I removed the EGR valve and soaked the diaphragm shaft
with WD40.

2) Reference potential clogged EGR tube; I couldn't find a speedometer cable, so I used nylon monofilament line (approx 3MM dia) used on line grass trimmers. I fed the line from the valve side and hit what felt like an obstruction about 4 feet in, and worked throught it another 3 inches or so. I don't think I made it all the way through however. Getting to the tube from the other side is a bear from the top side, and not having a lift, nor the desire to take the top of the engine apart to get at it, I reinstalled the valve.

I cleared the fault, and a dozen trips and 100 miles later the check engine light remains off.

So...not really sure whether I cleared an obstruction, or just improved the EGR function with lubricant, but the problem appears to be solved.

Thanks much for your help!

__________________
Dave Gillespie
1994 E320 Wagon