So, I bought a new 2010 double Cab 4WD 4.6 a couple months ago and may have made a BIG mistake in not getting the 5.7 liter. I read all the raves about the new 4.6 and thought gee, since my travel trailer is a Passport Ultra light that weighs only 6000 lbs fully loaded, I should have no problem towing with this truck which is rated for 8800 lbs tow capacity. BIG DISAPPOINTMENT on my first trip. Namely, the truck really strained with the load on hills by dropping back to 3rd or 4th gear while jumping up to about 4500 RPM's to maintain 55 MPH on steep hills. Also, averaged only 8 MPG for this trip! Am I screwed or could something be wrong with the truck? Thoughts? Similar experiences?