Well my gas mileage is still hovering at 15-16mpg, stock tune, and stock t-stat, and oem spark plugs. Went over the exhaust today looking for any leaks, found nothing. Only things I have left to try are going back to iridium plugs or changing out the O2 sensors which aren't throwing any codes. Maybe I'll just swap the front and rear sensors around and see if that does anything. I dunno, I threw the jet chip back on the truck after my last tank showed 15 mpg w/ the stock tune, that is how desperate I am.