sherman

If you are still running a stock intake filter and box,you are a candidate to drill out the stock air box and replace the stock filter with a new one, try it there is no cost other than your time. The stock air box pops right out,drill it out and replace. Don't change any thing else. I did it and gained 2 mpg. If it works then add a Quad Xzt tow box for another 1.5 mpg gain. Keep the rpm at or below 2500 rpm and above 1900 rpm when climbing steep hills.When on the flats keep your rpm at or below 2000rpm.It sounds like you have towed enough to have the engine some what broke in so the break-in excuse does not apply.