I agree with All2kool, if you drive like there is no tomorrow, even a 4 cyl. will have low fuel economy.
Having said that, you could try cleaning your MAF sensor too. Use only MAF cleaner or electric contact cleaner available at most autoparts stores. Take a look at it under a magnifying glass and you should be able to see some dirty on it...
Perhaps even a vacuum leak... Make sure all the hoses running to the throttle body are OK. If you have a live data capable scanner you can take a look at the LTFT's to make sure if you PCM is adding too much fuel or if something is out of the normal.
Oscar.