Average Miles to a tank of gas?

extrapolating, 240 ish.

any codes? bad O2's, Maf issues, ECT, ACT out of calibration, bad EGR, etc can cause richness.

you are not exactly stock - wonder if that has anything to do with it. :)

good luck.
 
I get 15-18 MPG depending on how I drive. 15 MPG is driving pretty fast and heavy acceleration. 18 mpg is driving like my dad. Caravans beat me off the line... :( But it softens the gas bill.