I just swapped in a set of 4.6 5.4 5.0 yellow ford injectors and picked up a couple mpg in my 99 5.2 5 speed, I have it up to the same mpg as my last V6 5 speed truck did. I have also added cold air intake, electric fan, 17" RT wheels with narrow tall low rolling resistance tires. The injectors made the biggest difference and cost me $50 at the local JY and 30 minutes to install. Idle is smoother and I can lug it around at lower RPM now without chugging.