[dreager]

I think your referring to the EGR valve (big round aluminum jobby). $200?, I don't think so, and you can get used also. If it constanlty idles rough usually its the throttle position sensor. Also take the PCV valve off and see if it rattles, replace if it doesn't.
You paid good money for a new clutch, I'd have them adjust it before warranty runs out.
A Haynes manual tho' not as detailed as I would like, (unless you're ripping an engine) is ALWAYS good for finding most sensor locations etc. Well worth $20.

Good luck.