I've got a 5.9, 96 1500 with only 16000 miles. I usually average 20-17 MPG during the fall/summer/spring season but mileage goes in the tank over winter, down to 14-15 MPG. More sitting, less driving. I also spend a lot more time stomping on it to get the heck out of the intersections (no traction) in the winter though. So my answer, ease up on the foot!
