rough idling

I've got a 93 Astro that shows 223,000 on the odometer, but I think the engine has had some major work done on it. The van ran like a top when I got it, but I evebtually had to replace the EGR valve due to rough idling and the check engine light coming on. After replacing the valve, the van ran great again. It is again idling rough, and has been for about 2 weeks now. The van runs great in all areas except idling. It's not as bad as it was before I replaced the egr, a nd the check engine light does not come on at all. I bought nwe plugs and wires which I haven't put on yet. I don't know if the plugs are bad or what. It's strange that the van smokes when you crank it after sitting all night or all day at work, but it doesn't ever seem to be using any oil. I guess these are bad valve guide seals, because it doesn't smoke one bit after the initial long sitting start. When the egr valve was bad; it finally got to where it would try to cut off at a stop light,ect,. this time doesn't seem as bad, and no chk eng light on. Does the van need a tune up or is it possible that the egr is again clogged? I was advised here at the forum that after putting in a new egr that it's been known to clog again on some folks. Thanks for all the help.
John Sr.