Run some fuel system cleaner for a few tanks and see if that helps you at all. Be sure to add it to the tank at the gas station before you fill it, then run the tank as empty as you feel comfortable.
If you use the cheap gas (any grade, Arco-type) this can hurt your fuel economy also, because A) it's "watered" down with ethanol, using more fuel to get the same power, and B) because it has a tendency to build up more carbon deposits in the heads.
There is a product called "Seafoam Motor Tune-Up" that does an awesome job removing the carbon deposits. It can also be used as a fuel system cleaner or crankcase cleaner, but I buy it for the carbon cleaning. To clean the carbon, it has to be added to the intake while it's running, so be sure you follow the directions and use less than a third of the can per treatment.
Also, 0-10mph is where the worst fuel economy happens. So the more you stop, and/or the faster you get going, the worse your mileage will be, though this may not be your case.