I may be able to offer some help. I have just replaced the EGR Valve on a 2002 expedition with the 4.6 engine. If the motors are the same from 01-02 here's your answer. The EGR Valve is located on the driver side of the motor. It is all the way at the rear of the motor near the firewall. The valve has a circular top with a vacuum hose attached. there is an outlet/inlet pipe below the top. There is a metal hose attached to the outlet/inlet. This hose runs up from the exhaust. I started by removing the plastic shroud from the top of the motor. Then I removed the nut on the rear bolt of the assembly to move the hose support out of the way. Next, I removed the rear bolt. Leave the front bolt in place for now. There is a nut on the top of the metal hose that comes up from the exhaust. Loosen this nut and remove the metal hose from the bottom of the valve. Now remove the forward bolt. Here is where I apparently missed a step. After replacing the valve I cleared the trouble code. The service engine light soon came back on. After speaking to some mechanic friends I was told I should have removed the metal hose and cleaned out the carbon or at least have run a pipe cleaner through it. NOTE: I purchased the replacement EGR Valve directly from Ford. I was given the wrong part. The parts guy said it was an error on their catalog. I suggest you take your old valve to the parts counter with you to avoid this problem.
I'm not a mechanic but this is how I got it done. Maybe others can give you better advice.
I had the same problem with my 1999 Expedition so we removed the EGR valve and cleaned out all the carbin and reinstalled EGR valve Undo the batt for about 10 min. to clear computer