Another quick, easy, cheap thing to check.  If it is throwing an EGR code, there is a steel tube running from the EGR valve to the head.  IIRC, it is held on with four 10mm bolts (2 each end).  This tube tends to collect carbon and gets plugged at the head end.  Take it off, run a wire through it and clean it out.  If it is plugged, you will need to clear the port that it connects to on the head also.

Good luck.