OK, an update to my problem, if anybody is interested. As I said I flunked the NOx part of the smog test, the solenoid is working fine, replaced the EGR valve, cleaned out the EGR tubes under the throttle body and flunked again. I reduced my base timing from about 11 degrees to around 8 degrees and still didn't pass, but much closer.
Since then, I poured in two cans of Berryman's Chem Tool into a half tank of gas, about 10 gallons, and drove it at around 70 mph for about a hundred miles. Tonight I sprayed a can of Seafoam into the throttle body, mostly into the EGR tubes and a little at a time with a start in between and lifting up on the EGR valve diaphragm after each start. I let it sit about 5 minutes between each shot.
I think I've come to the conclusion that everything is fine and clear between the EGR valve and the throttle body but the valve just isn't getting what it needs from the other side ... the exhaust.
When I lift up on the diaphragm it stumbles but doesn't die, as I think it should at idle. Any thoughts on that?
I have never had the intake manifold off so don't know just what's on the exhaust part of that and its connection. Maybe just run a coat hanger through and yank around? Anybody been there and done that?