emission control causing rough idle?

I would start by disconnection the vacuum hose to the valve and see if that helps the idle. If so, you may have vacuum hoses hooked up wrong or a bad vacuum amplifier. You can also operate the EGR valve by hand to see if it makes the idle worse when it's open (it should). Just reach around the back side of the valve and pull the rod away from the intake. You may want to do it with some needle nose pliers or a screw driver if the engine is hot so you don't burn your fingers. I've seen those valves get bent and not close all the way so give it a good look to see if it's straight. I would repair the system rather than just block off the valve. You could have other driveability problems as a result. They were designed to have that valve working and if it doesn't, you could have an air/fuel mixture imbalance. Now if you want to rejet or change the carb for a non-EGR engine.....knock yourself out.