I work at a small private garage and a customer brought me a 2005 F-150 5.4l fx4 4x4. It has 5500 mi. He said that he took it to the dealer to get it reflashed for a shifting problem and now his gas mileage has dropped from 15 to 12. Has anyone else noticed a drop in gas mileage after a dealer reflash??

 

mine went up with the recent increase in temps.. im gettin 21mpg now. also i went from an old style aluminum MAF to the new black abs plastic one with the newer reading sensor and got 1mpg increase and feels alot better.