What are you NOT telling us? Do you have an add on tuner or fueler? Has the engine light come on? Have the exhaust tips turned black? When you add together your miles traveled on this tank and your miles to go to empty, what is the total? Have you changed headers and disconnected the O2 sensors? Have you fueled up just before arriving home and compared the fuel level at shut down to what is in the tank the next morning to confirm no seeping leak? Is the engine hard to start when hot? How many miles on the spark plugs? Air filter? How well is the engine running other than apparent high fuel consumption? Are you going by actual fuel added or by fuel gauge indication? How many miles to work?