your not alone. i have an '01 7.3l with a afe intake, mbrp exhaust and the edge evolution programmer set on 80 hp, and the mileage sucks too. i have 295/75r16 tires, and whether im on the highway or driving in the city, i get 12-13 mpg. without the programmer i get better, like 16 or so. the problem is i cant keep my foot off the pedal, with the programmer in. there just something about blowing soot all over a mitsubishi eclipse after you smoke them off the line, literally.