I have the Edge Programmer as well, and have been averaging just over 16 mpg with a mix of city and highway. If you want to lighten your foot off the gas pedal, have your edge display Instant and Average mpg's. Works for me!

 

I have a 04 with the 4.6l on the highway last trip i took showed 23.4 mpg running 70 mph

 

I have a 4.6l also with 3.55's. No tuner. 64 mph, 1600 to 1750 rpm's my "sweet spot" Best highway mileage 18 mpg, hand calculated, with 1000 lbs in the bed.

I need to get me some of that 23.4 mpg kool aid. And with a 5000 lb truck besides. WOW

 

2004 4x4 5.4 with 90000. I just changed the sparkplugs in mine. Before change I got 16mpg and after 17mpg. MC Sp515 plugs, everthing else is stock. Mostly freeway miles really happy with that.