emission control causing rough idle?

That valve is only 25 dollars at autozone, I was just thinking of ways to eliminate unnecessary things, haven't checked vacuum at idle, cause it too cold out there this week. When it warms up a bit, I'll check it, and put a timing light on it again...if thats good, I guess I'll get a new EGR valve.The engine runs down the road good, lots of power, the only thing that bothers me is at idle, under a load, the wheel and dash vibrates, drives me nuts....