Good thread. I have several techniques I use.

I must say though, that you have a 5.4 in a F250 which are notorious for reving higher and harder then an F150.

Anyway, with all the power adders I've bolted on I didnt see any real significant change in MPG, mainly just a notice in throttle response and interstate MPG. I've added the K&N FIPK, Helix Spacer, Flowmaster Exhaust, and just installed the Edge Evo.

With gas the way it is, I never carry RPM's over 2000. I start slow at red lights and always remember to keep the RPM's low. By doing this I can squeeze out 15mpg in town driving. On the interstate I regularly see 17-18MPG out of a 2001 Ford Screw 4x4 with a 5.4l.