poor fuel enconomy...plenty of power.

[RatRod]

i recently converted from driving a 12v cummins to a powerstroke and now im not so impressed with it. truck only has 140k but eats through fuel. im only getting 12-13 miles a gallon. i figured i had a leaking injector but there is no fuel in the oil and it doesnt smoke once the truck is warmed up. i also checked for fuel in the valley and its dry as a bone. when i bought the truck it had been sitting in a old cattle barn for time, i mean a good amount of years. ive been trying to run 5 or 6 tanks through the truck before i changed the filter over but i was wondering if anyone had an idea what would cause this. also i have checked for dtc's but there isnt any in the truck, under current or history.

[JSchuricht]

Start with the basics. Clean air filter, preferably something that flows better than stock. Remove the restrictions in the exhaust, cat and muffler. Fuel filter and a chip for mileage.

Also, a bit more info would be helpful. Tire size, gears, driving style, in town or highway?

[RatRod]

3.55 non lsd, 245/75/16, mostly back road driving. i did up grade to a dana 60 king pin in the front with all new brakes so i know its not a caliper hanging up. i just tossed a new OE style air filter in it. i do get after it from time to time.