79 pontiac 301 2bbl. Engine had been running great, smooth idle, quiet etc. Just started to run rough at idle, not like a cylinder droping out but like idle adjustment off on carb. Carb was reabuilt not long ago and is fresh. Touched up the idle screws, no help, checked for vacuum leaks (and this car has lots). The only thing that seems to smooth it out is to move the air valve (like when the choke is on). This tells me it is running lean. Could the egr valve not closing exhibit this symtom?

Yes, it could be the EGR if its not closing at idle. I'd check your plug wires and all those little plastic vacuum lines too.

That could be the problem,( the EGR sticking or the passages to it are clogged) but you also could pull one spark plug and check if it is black. If they are black that means that you are fouling out your spark plugs, this could be caused by the idle solinoid going bad. at least thats why my truck idles weard. A quick fix or test is turn your idle up to 1000 or 1150 so the car is never at idle. If that solves your problem then you might have to buy a new carb. I don't have the money for a new carb thats why I haven't fixed mine yet. I could be completely wrong though.