EGR valve?

skim1040

work in progress
So, as of late, my car has been having some issues idling. I have checked all of the accessible vacum lines and I don't see any problems. But, the reason I don't think it to be a vacum leak is because the rough idle isn't consistcant. Sometimes it idles fine, others it doesn't idle at all.

Could this possibly be a carbon build up, or something of the sorts on the EGR valve not allowing it to seat and seal properly? Or have I overlooked something simple here?

thands in advance!

Skim