Ford Repair: Expedition EGR Code, pressure hoses, ford expedition

Question
Thanks again for the help.  I finally broke down and went to local Ford dealer.  He also suggested the PDFE sensor be replaced but first pay $400 to remove the intake and clean the EGR ports because of build up.  I wasn't able to do it just then but if it ever gets to affect performance I'll have check into it again.  Was he referring to the throttle body?  Could I clean the ports with just removing that?  Sound logical?
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-----Question-----
I have a 96 Ford Expedition (4wd) with 4.6L V8.  A month ago the check engine light came on with code 401.  Checked all vac. tubes, wires etc. and found nothing.  Removed and cleaned EGR valve.  Disconnected battery but fault came back.  Resistance was alittle low on EVR sensor so changed it.  Fault went away but came back again.  Got desperate and replaced DPFE senser because I read it goes bad a lot.  Fault went away for week and then came back as 402 error.  Thought only reason for such code was EGR valve so went a replace it (it did look bad).  Tried to reset by disconnecting battery but fault came back.  Now I'm at a loss.  Engine runs great otherwise, no other issues.  Vac. lines and hoses still look good.  HELP?
-----Answer-----
P0402 indicates you may have egr flow at idle. A scanner would be best to daignose this, however you can check the DPFE pressure hoses and the EGR pipe for blockage. If the engine idles ok, there is either a problem in the wiring, the hoses are blocked, or you have the wrong sensor.

If you didn't use a Ford or Motorcraft sensor you may have a bad one.

Answer
I think I would remove the throttle body to clean the egr ports, if it looks bad enough then do the rest. Have to admit I haven't had a manifold off one of these, so I'm not sure there are egr ports in the manifold. My understanding of the system is the egr feeds directly into the intake air stream.