Got a used 2001 limited trooper, and am not happy with the gas mileage. Has anyone with the same motor gotten better gas mileage, and how??? I put 45 lbs in the rear tires, and 40 in the front, ran a bottle of injector cleaner thru it, checked the plugs, new air filter, but no changes. Could there be anything I can do besides park it to improve the fuel economy???