That is the worst type of driving in our rides. Short stop and go commutes are brutal on fuel.
They are a heavy beast for a small truck. It takes a lot of energy to get them going, and then stopping uses energy also. I use the driving coach, really makes me aware of my led foot, and concentrate on driving smoothly.
My truck does very good on longer hauls, and the farther I drive it the better it does.
I work on Panama City Beach, and often in Springbreak traffic my mileage will drop to 9-10 miles per gallon because of conditions.
Maybe mapping out a different route would help you?
Some of the things Ive done to help my mileage are a custom side dump magnaflow exhaust, cold air intake that has thermal blanket installed, preheat bypass, Redline Racing synthetic gearoil,0w30 engine oil,tranny fluid, irridium plugs, and less agressive tire tread.
Switch stations. Different fuels make .5-1.5 mpg change in the fronty.
With your mileage, you may want to do as I do before installing plugs and use Mercury Marine PowerTune in the intake duct, and Quikkleen in the fuel tank. Coking buildup on intake valves and in chambers kills efficiency.
Also driving that short of a distance your cats dont have time to reach full temp and are coked up as well.
Have you ever bombed the fuel system? If not its time, while doing the service. Multi valve engines have to be cleaned out dont you will have troubles.
Mass air sensors and 02 sensors get dirty, and can alter a/f ratio.
What a/f value does your BD display at steady cruise?
Also, check your brakes for drag. Dosent matter if the BD makes 50 more ponies, you run around with the brakes partially applied its not going to help any.