I hear you Chris. I have a 2000 F-250 diesel. similar to the truck you showed, except it has teh 7.3 liter. I get a consistent 13 mpg, but I have bigger wheels and tires, and that is with towing my trailer, which at full weight is about 8500 lbs, around through town.
I have a really good friend with an '04 that is getting about 18 without a chip, and it is exactly like that one, except for the yearly update stuff.
I was goig to buy an '05 at teh end of last year, and went on the lot, and could not find one that I liked. They all had the wrong combination of stuff. So I just kept the same truck at 145,000 miles, and will keep plugging.
I also have a 5.4 in an 04 f-250. A stripper work truck. It gets about 13 MPG as well, but it leads a hard life with a lot of idling. (about 2/3s of the time it is usually running, it is idling.)
Just for comparison sake.
Scott Stone