9,000 miles, I have not seen anything above 14.9 - empty. 10 MPG towing 30ft trailer. I have been to dealer twice now. No help there - they have been good about it, but no help. They suggested a programer. I have installed a KN filter and superchip, runing in safe tow. I was told safe tow will offer the best mileage. No change. I checked tire pressure, all is good. I love this truck but fuel prices are going to make me park it.
(I'm not comparing, but my son has the Ford 7.3 we just drove to NM. About 950 miles - towing a small trailer about 1,000 lbs. Got 29 MPG!!! I wouldn't have belived it if I didn't see it with my own eyes!!!)

Any suggestions would be greatly appreciated.

thanks
Larry