Thanks to all of you for the help my trucks is not showing the slow tol et off symptoms, yet I'll go test it the next time I drive it and see As far as the fuel mileage I towed my 24 Ft Pace enclosed trailer 1300 miles one way to Tuscon,AZ with my old Duster in it at more than the posted speed limit most of the way The wind was blowing, it was cold and the heated seat where on most of the way, it averaged 10.78 MPG going down and I haven't figure out the return milage yet I have been negligent in changing the fuel filter, I've changed it twice so far I do buy most of the deisel fuel at a local station that pumps a bunch of fuel everyday, two big tankers a day usually, so hopefully that helps. It will get change more often now Thanks again to all Cab