I'm in a similar situation (1996 1500 4x4/5.2/auto/hemifever program running the lowest setting with 87 octane gasoline/2" lift/4.10 gears/285-75-16" tires, roof height fiberglass topper) and getting around 10-11 mpg. I've also got a 50mm Fastman throttle body & factory air cleaner set-up, low restriction magnaflow muffler. Very recent rebuilt fuel injectors installed and Melling high-volume oil pump, and a recent new fuel pump. It's not a slug, but it's not a speed demon either. Aerodynamics of a brick - got it. Plenum replaced way-back-when.
So dumb question, but what do you all consider a "tune-up"? Would my mpg improve if I ran a higher octane gasoline and the next higher hemifever program setting? All the "parts" on the throttle body (the plug-in things) are factory originals (and I gave the throttle body a good cleaning when I had it off when replacing the fuel injectors).
I love my truck (just over 200,000 miles) but would love a few more mpg.
Last edited by armynurse; 07-13-2014 at 10:33 PM.