What would cause the truck to lightly lope or surge when idling? Its hardly noticealbe but definetely there. Truck is all stock except a 4" exhaust system- no programmers or tunes.
so i have noticed lately that when the truck is warm and idles down the rpms surge about 50 or so rpms so the gauge says. no egine lights are on or anything like that. also i have noticed my gas mileage decreasing and im driving the truck like i always do. im pretty new to the diesel world but...