yeah, ignore the wires part. i'm not too familiar with the 5.4 yet. i've mostly driven carburated sbc's. i work on the road a lot, so i drive the wife's grand prix. i told her to have the plugs and wires changed last time she took it to the garage. i assumed it still used wires. hey, i'm a lineman, not a mechanic! thanks for all the replies guys. i'll just assume he was bs'n me and love my 14 mpg! who knows, maybe after i replace a couple things it'll help.

 

A.) replacing stuff back to stock (fuel filters, plugs, o2 sesors etc) will return lost mileage
B.) Not all trucks are identical, one can get 16 and another 18 in the same conditions
C.)Keepin' the foot off the gas changes alot
All in all rare but possible to get good mileage (23) I got 20+ on the highway before I dropped cylinder #4

Note of oddity In my explorer I get better highway gas mileage with my trailer, when lightly loaded- so aerodynamics come to play. He may have had some weird tool boxes or something that changed the airflow collapsing over the bed.

Or he was full of crap...

 

Ditto... but mine is a 1998 F150 Ext. Cab, 4X4, I get an average of 13-14 mpg's in a rural area, very hilly, with alot of stop and go.
Like Jethat, my truck pretty much runs perfect. Preventitive mait. and I keep up on the repair's as it is needed.
You sure your friend doesn't have a Chevy S10 to get that 25 mpg.

 

On average, - 360 miles on a tank. I'm pretty sure I have a 25 gallon tank, but usually can only get about 22 in her. That should = about 16 mpg. Well it's close enough for me . I figure the motor will be broke in @ about 300,000 miles, so I might see a slight increase a little further down the road

 

my little 5.0 gets me 23mpg at 55mph on flat land using my rear tank. i'm heavy footed when it comes to accelerating. using my front tank for some reason gets me no more than 15mpg so i got some diagnosing to do when i get home for christmas break. thats with a cam, cai, dual exhaust and a worthless chip.

 

That's pretty good !

Maybe the front tank is leaking into the rear - That didn't sound right

I can't really floor it around here without running over someone or something. - Hell it' keeps up with traffic just above idle. But, I cruise as fast as I can go on the e-way - without getting a ticket that is.. Speed limits 70 mph here , so I set cruise about 79 mph and still get passed every few secounds

I could probably get 18 mpg if I backed off a couple knots - No can do :o