I have a 2003 5.4L, 2wd, reg cab. I pull a 6.5X12 single axle trailer, with three mowers most of the time. My lawn service is on tight routes, so don't drive very much (5,000 miles/yr). It now has 47,000 miles.
MPG is horrible, 8-9 MPG, never reach 10 MPG. I drive very gingerly, but lots of stop/go, residential neighborhoods. It has plenty of power for my work.
It has been trouble free, until last Fall. I have an oil leak around the head gasket, and front cover. I was planning to get it fixed, but learned the repair requires pulling the engine, or removing the cab -- probably about a $3K job. I am marking time this Winter, as I drive it very little during Jan - March. The leak is not debilitating, as I need to watch the oil level and top off as necessary (2-4 weeks). I will make some decision by early March -- replace, repair, or continue to drive knowing of the problem.
Maybe some changes were made between 2003 and 2009, to, (1) improve mileage, (2) remedy the oil leak (I understand it is not uncommon). Therefore, take my experiences with that perspective.