My 01 Focus S2 with Zetec was giving a bad DPFE code and had all the signs/symptons associated but the car was still very driveable. Yesterday it got worse, car would want to stall when idling and occassionally would have no power for a few minutes then clear up and run fine. I changed DPFE and reset computer by unhoooking battery for a hour last nite. This cleared trouble code, but I am still having same problem (although a little better than yesterday) on a 30mile ride into work this morning it ran pretty good when cold, but once it warmed up and I started hitting stop and go, it started stumbling bad, wanting to stall, then it had no power for anout 5 miles (in middle of nowhere) so I kept chuggin on, then all of a sudden it started running great for a few mile befor acting up again. And again no trouble codes being given, check engine light is off.
Anyone have any ideas? I am considering going ahead and replacing EGR valve itself and replacing fuel filter? If i disconnect airhose to EGR valve the stumble stall shoud go away if its the EGR, can the EGR get stuck open? Could dealer have given me bad dpfe or one with wrong calibration?
Thanks for anyinput.