I just bought my truck a month ago about 150 miles from home and on the trip home my fuel milage was 13mpg . a couple of days later I had the hood up and was looking things over while the motor was running, I noticed that there was fuel dripping from the fuel filter area, shut the motor off and the dripping stopped. Took the filter and heater off and found the heater O ring flat and shrunk. Could'nt find a new O ring any where at the chain auto parts so I put the seal back with a little gasket sealer, put it back together w/new filter and NO LEAK! Went for a 200 mile jaunt and got around 20mpg.
Just a thought,
newbie, Dan