Fuel mileage. cannot get more than 14 mpg (city use)
* New Autolite plugs
* cleaned throttle body
* changed fuel filter
* intermittent but regular use of "Sea Foam" fuel treatment
* Cleaned max air sensor.
* Driven responsibly

Engine runs smooth but still less mpg than a friend's 4x4 F150
Any successful ideas on how to correct.

 

Nope, from everything i've read the most people typically get out of the 4.0 is 21 highway.