re: Ot mechanics: gas mileage issue

Just filled up...went from about 31 miles to the gallon now to 24 to the gallon. You don't change air filters in the focus model I have..supposed to be for the life of the car..but I did check the health if it..still in green...I guess I was persuaded into the high mileage..didn't know it would make a difference..I will give it a few more weeks..maybe I need a tune up??