I hear you!! 10mpg average and 12mpg highway is what I'm getting right now. Before I started having problems, (Burned valve on passenger bank) I was getting 17-18mpg highway with 3.73 gears and 33x12.50/17 Mickey's. About 13mpg in town. I made a trip to Orlando and averaged almost 19mpg, but that was staying strictly at the speed limit and stock tires. I let my son drive it for a couple of years and then parked it due to the burned valve. It stayed parked for about 4 years until I decided to drop a crate motor in and put it back on the road. The dealer that put the motor in was supposed to give me a turn key truck for a daily driver. Fix all the codes, track down the problems, do a bumper to bumper service, and deliver a truck that I could just get in and drive. Long story short, the dealer (Bud Shell Ford in Dexter, MO) wouldn't return my phone calls or emails and so far I've had to replace the brand new (Autozone) battery they installed, rebuild both drive shafts, replace the idler pulley and tension arm, plus all the new stuff I mentioned in my initial post. It's been one heck of a journey, but I'm learning some stuff along the way. I'm sure once I get the EVAP system lined out it will improve some, I just don't know how much.
I'll update this thread as I journey along and find other issues. I'm sure once I replace the canister and solenoid (hopefully this weekend!!) I'll end up having to drop the tank, new fuel pump, new tank pressure sensor, new vacuum lines, & new vent valve. I guess once I get everything replaced I'll evaluate whether I keep throwing money at it or not. More than likely I will simply because I love the old truck and the newer ones just don't do for me what this one does.
