Well, I finally took the time to look at my truck last weekend. It had a P0401 code. At 34K I had a hard time thinking that there was anything plugged up causing this.... well I was right and wrong at the same time. I pulled the throttle body off and the EGR ports were almost completely clogged. So I cleaned everything thoroughly and put it all back together, reset the computer and all was well.... for about 50 miles when the light came back on. So I started checking EGR sensors and the first one I checked was the DPFE sensor. Bingo!! With the engine warm it only had a signal voltage of less than 0.1 V. So after figuring out which one it was (the black plastic one) I replaced it and reset the computer again. 650 miles later and no light. I think I finally got it and I seemed to have picked up a little mileage in the process too (20 mpg highway now).

The only question about this that I have is that I know Ford redesigned that sensor. When I checked the voltage on the new sensor it was only about 1 volt as opposed to what was quoted from the Haynes manual. The manual only depicted the aluminum one. Is this a problem or are they different wrt voltage.

By the way, got the sensor from the dealership ($24).