You're right Jbrew.....In my case it was both. Thanks again

 

Yea , I recall when the 401 was strictly a DPFE problem. It was caused by excessive moisture with the metal and plastic sensors. Then , sometime around 2005 the 4.6L's began revealing plugged EGR ports in the plenum body (elbows). Only the 4.6L's plug the ports, not the 5fours or 4twos. So yea, a 4.6L specific problem.