Just found this site, was member of a Ranger forum in the past. Looking for some info on 05's 5.4 engines. Mine runs fine, except when I go to pass. It doesn't matter if I am on the flat, down hill or up hill. It just gets very sluggish, almost like it is bogged down. The RPM's rev up up by for a few second I just don't pick up speed. It is serviced regular and has 56,000 miles. Second question is the yellow engine light comes on, this is the one that is an outline of a motor. I checked the gas cap (Jeeps are famous for that) and had my mechanic put on the scanner. No codes come up but he is able to reset it. Stays off for a while and comes back on. Checked service bulletins and the only thing he found is something related to one of the cats or O2 sensor. Anyone else having any of these problems. Sorry a little long and yes I searched before posting.

 

Someone will chime in more knowledgeable than myself eventually. I can however tell you that this might be something to take it to the dealer for. Reason being is that just because your mechanic can not read the code that the truck is storing, the dealership has all the appropriate equipment/training that can evaluate the conditions.