I'm not sure if yours is the same as mine, but i'ld suggest every second or third tank of gas get some fuel-ingection cleaner from an auto store like pep-boys or somewhere like that and dump some of that in there. If yours is indeed like mine, after you do that a couple times your gas mileage should improve. Mind you, mine's still pretty bad for my car... only about 16.2 mpg right now, but i still have work to do... and that's a lot better than the 10.5 i got when i bought my car in January
If your car is different than mine, sorry, i'm kinda new to cars...