poor gasoline mileage

If the thermostat is not working properly, the engine will run cooler than normal, and fuel mileage will drop. Old oxygen sensors will also have an effect on fuel mileage. Have the engine codes checked also!

Do the checks that munkyrench said, but Texas mandated ethanol in the gas about 2 years ago, that could be part of it. Also, run some injector cleaner through it and some valve train lubricants. Check that the Air Filter is staying clean and check the pcv valve, if it is full of oil and gunk, it may need replacing also. Remove the air inlet hose and check your Throttle body area, use some carb cleaner to clean it up if it is dirty.