DPFE stands for Delta Pressure Feedback EGR.Now for the directions to fix it...
It is an emmissions control for the EGR system. What you want is the backpressure transducer.
On the 3.4L SHO engine, this is mounted on the rear of the intake manifold/plenum. There is a bracket which holds the DPFE, and the EGR regulator solenoid, and the solenoid vacuum valve. The DPFE is the rectangular aluminum part, held by two nuts. It will have two vacuum hoses on it and an electrical connector with three wires in it. It is easy to change, and the p[art is in the $65.00 range.
From taurusclub.com: (http://www.taurusclub.com/forum/82-maintenance-repair/106992-changing-dpfe-sensor.html)
Moving on, replacing the DPFE is very easy. I don't have any pics, because I don't own a Duratec, but they're all basically the same.The best site for V8 SHOs...
1) Disconnect the negative cable from the battery (this will solve two issues: it'll clear the codes from the computer's memory, and prevents accidental starting when working underhood.) This should take an 8mm or 5/16" socket or wrench.
2) Once you locate the sensor, unplug the electrical connector and the two hoses that are on the sensor. Don't worry about mixing up the two hoses, they're different sizes.
3) Remove the two screws holding the sensor in place (8mm or 5/16" socket or wrench), and remove the sensor.
4) Install the new sensor, plug the hoses onto it, and plug the electrical connector into it.
5) Reconnect the negative cable on your battery.
6) Start the car and let it re-learn idle settings, and then take it for a ride.