i own a 98 rangerxlt v6 3.0 4x4 (same truck in 2wd) first make sure your tires are the correct size, that could make all the difference in the world. the door panel should say 235 70 R16. then make sure they are properly inflated. again the door panel should read 32 front 35 rear. i have mine set at 35 all the way around. a little bumpy ride but so what. also you MUST drive like granny! meaning easy on the gas pedal & keep the RPM's down. ihave also upgraded my mass air flow to a cone filter ($25 @ autozone) increased gas mileage consists of a lot of little things and is tipically not just one thing. make sure the truck is running in tune... oil, plugs & wires avoid short unessesary trips. avoid engine idle. 60-65MPH / highway. when i got the truck i too was only getting 13-14.5 MPG but now the truck gets a consistent 17/18MPG. remember to drive like granny.