Chuck, If you type "gas mileage" under "search" in the Performance section you will see tons of posts with your same concern. There are tons of suggestions, but, in my opinion, no remedies. People suggest spark plugs, muffler/exhaust upgrades, intakes, oil upgrades, etc. You might get a bit more throttle response/acceleration with these upgrades, but most aren't seeing measurable gas mileage improvments. I think most are getting what you are. My averages are around 230-250 before the light goes on. As far as the people who say they average 300 miles, I would like to sit in their X's and watch it hit 300.
My advice, enjoy the truck and drive it the way you want! Life's too short!