Lightly loaded with my zf-5 and 410 I get 15-16 if I pull the 55mph prius blocker action on the highway. I know my fuel system is tired. You take some lumps when you buy a $800 truck.
I am waiting until spring(I hope) to do batteries and all the fuel system, injectors, lines, IP and liftpump, seals. I want to put in a big marine racor. I just did the fuel tank switch valve. It is now a fancy gray color but otherwise the same, not black like came off it. Makes me not feel so bad about it costing almost $300 from ford.
I will scrounge the boneyards for some 355s and a turbo. I want to see 20mpg.
I just replaced the front springs from General Springs. Energy suspension Poly all around. I fished most of the "showerheads" out of the tanks. I did a SMF swap from Ft. Wayne clutch with kevlar input bushing. The dual mass was completely worn out and rear engine cover was leaking at the driver side, contaminating the clutch, making it jerk when starting out. Installed a new teflon main seal while I was down there.