I have 1999 lightning PU. At low speed, between say..... 25 and 45, and under no load, just puttin along, it will seems to miss and surge. No real ryhme or reason. It is very prevailent after a fill up. At times the Service Engine light is on for a day or two.
OK.. figured it out.
Took it to Auto Zone and had them read the codes. 1 code stored. Excessive EGR Flow. Disconnected the vacum line to the EGR valve and reset codes. Truck ran much better. Service light came back on, had codes read again. 1 code, insufficient EGR flow.
Removed and cleaned EGR with carb cleaner. Will let you know but it seems to be cured now.
mimsand, read my post on HD cure. May need to check dpfe sensor. It works with egr. Ford dealer here keeps many because it is a very weak link in all model Fords.Hope helpful. Rudy 03'HD, 2000 EXP., 96' Cobra, 94' f150 4x4, 2000 zx9r