Diagnostic Aids
WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
Inspect for excessive deposits on the EGR pintle or seat. Remove the EGR valve and inspect for deposits that may interfere with the EGR valve pintle extending completely or cause the pintle to stick.
If the condition is intermittent, see INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 3.4L AZTEK & RENDEZVOUS article.