Well, you've got pretty much the same engine/gas tank as I have in my 2007 31' Forest River Sunseeker. I was hoping some of the older and wiser forum contributors would chip in with some info. I drove mine from the dealer's lot to my driveway (60 miles) and have been tweaking it ever since, getting ready for the road trip to Alaska. I have read some other posts about older versions of this engine blowing spark plugs. Hopefully for you and me, Ford fixed this problem. I will keep checking back and will let you know what kind of mileage I get once we start rolling.