Diagnostic Aids
WARNING: This page is about a different car, the 2003 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
Check for excessive deposits on EGR valve pintle and seat. Remove EGR valve and check for deposits that may interfere with EGR valve pintle extending completely or cause pintle to stick.
If the condition is intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.