'01 Ranger EGR problems

My dad's got an '01 Ranger 4.0 that had a code showing the EGR flow is insufficient. Cleaned EGR valve and reinstalled, code came back. Replaced the EGR solenoid, code came back. Replaced the EGR valve, code came back. Any ideas?

Did you replace the EGR solenoid or the DPFE sensor? WHen you cleaned EGR, did you clean the passages in the intake? These will carbon up and trip that code too.

DPFE sensor? Never heard of such a thing, mind explaining?

Passage ways were cleaned, and yes it was the soleniod.

The DPFE sensor tells the computer the position of the EGR valve. It is either a rectangle aluminum housing about 2 inches by 3 inches with 2 hoses and one wiring connection going to it. POr there is a small plastic box about 1 1/2 inches square with the same connecrions. It should be located near the rear top of engine. Good luck. Ford had an extended warranty on some 10 model years for 5 years or 50,000 miles. You may want to check into that. Part is relatively inexpensive and easily replaced.