I'm at 59K, changed plugs at 50K, had fuel injectors and fuel rails cleaned at 50K and my mileage is terrible. A Hemi Ram could do as well or better with in-town driving. Cleaned TB out at 55K, no improvement. Running 100% gasoline (10% ethanol drops me to about 13.5MPG from 15.5). The late '98 5.2 Magnum stock did better than the 4.7 does now. What do I try now? One of the "tuning boxes" and which one? 14-15.5 in-town/expressway is down from nearly 17 when new. What has changed? No codes, O2 sensors check OK. Tried different brands of fuel, .2-.3 difference tops. I'm figuring it with a calulator and not going by the overhead computer (which isn't much off). Hiway only mileage is still great...as high as 24.5 Tulsa to DFW, 2 stops. One for the toll booth and one pit-stop for me. It's obvious that idleing and stop-and go is killing me, but why? Tried Sea-Foam, no improvement.
