I would add, it is far easier to grandma higher mileage from a 2x than a 4x. My brother's 97 is identical to mine, except it's a 4x and he hasn't got better than 14mpg, but averages about 12-12.5 mpg. So Dodge Ram+4x4=crappy mileage and there's no defeating that equation.

 

assuming everything else is up to factory spec first: underdrive pulleys, efan, free flow exaust, free flow intake, manual hubs...there may be more but these should all theoretically alow for better efficiency which should both improve mpg, and quarter mile times. Probably a couple mpg's or so and about 3-4 grand of work to get it.

 

honest answer: install a vacuum gauge, and learn to use it.. that entails altering your driving style, which in most cases drastically increases mileage..

I'm dead serious about that.. I 'can' get as much as 15MPG mixed driving out of my rig when I pay close attention to the gauge, know the roads I'm running (when I can get by with NOT braking and coasting into stops, as well as when I can wind it up and not have to forcefully shave speeds)..

on the open highway- it's all about how tuned and less restricted (load due to parasitic loss).. the vac gauge ain't gonna help much..

keep your tires aired up- maybe even a touch overloaded.. keep your ride aligned.. run good clean fuel.. keep her tuned and everything balanced.. that is all you can really do..

 

stewie, you mentioned the O2 sensor change. If I've had the plenum problem and plugged cat, should I replace it just because? Regardless of CEL?
My wife gets 14.5 out of a 98 5.9 V8 2wd on 89 octane(carrying 800+ #s all the time) and she's not known for liking to stop, speeds sometimes(ok, most of the time), but does "granpa" off the line. She's in the country mostly, probably around a 50 mph average speed. I know her truck needs a tuneup and not sure about the "death flash". And I'm all for the rated pressure molded on the sidewalls of tires, maybe a few #s extra.

 

If you have a blown plenum and haven't fixed it yet, then I wouldn't replace the O2 Sensor until afterwards, it'll just get trashed like the old one, same thing with the cat, don't replace until the problem has been fixed.