I know I'm not the only person wanting to know how to improve this. Please post how many mpg's you are getting and what improvements you have done. So far I have add Hedman headers, crossover, 3'' straight pipe, MSD coil and Dist. Also deleted the EGR, and fresh air pump. I'm getting about 9-10 mpg.
You're doing good. Does it have 3.73 or 4.10 gears?
Mine was a '96 SC dually, 4.10/e4od and got right at 10 mpg regular daily driving. Back then gas was cheap so I didn't really care. Did put a Dynomax muffler on it. I also installed a Vortech supercharger later on, but don't recall getting any worse mileage. It's been years ago, and didn't really care about mileage then.
Mine is a 96 460 4x4 with 4.10 gears and a manual trans. All stock except for no cat & a Magnaflow muffler. I get 11 in town, 14-15 on the hiway & 11 towing a Jeep on the hiway in the mountains. Oh, and I live at 6500 ft. elevation!
I have 4.10 its an 96 CC dually it seems to be around 8 with a load and 10 without. I have not checked highway yet. My next upgrade will be a cam and adjust timing. By the time I'm done with the upgrades I'm hoping to get 12-15 hauling but thats a BIG hope.
The truck is all stock beside what I just did. I haul the gto with my 04 250, but my wife drives it now to haul her horses. I picked up this truck back in aug for 2300. Hoping I can build it up to haul the gto and my 84 cadillac. But if I can't get decent mpg, I'm going to sell it and get a power stroke.