Will a gas cap cause a rough idle/ feels like as miss? My 5.3 is 4000 out of Cpo warranty and is running rough. It came up with the the p0171 and p0174 code as well as the p0455/ tighten gas cap message on the info center. There's only 63500 on the truck and it's frustrdting. I don't want to drop 109.99 for the stealer ship diagnostic fee to hear the same thing that's written above. Thanks.
Mike
Mike