another gas mileage question

ok Ive searched but am unclear on what next...Im currently getting 10-12 mpg on my 96 4.0 2wd...no major mods...30" BFGs, Rustys K&N intake, throttle body spacer, tune up in last 6 months along with new O2 sensors...where do I go next to improve mpg...I was getting 15-17 about 3 months ago

Nothing I've done, K&N Intake, throttle body spacer, Doug Thorley Header, oxygen sensor, Gibson Catback system, new wires, etc. did anything significant for gas milage until I tried the E3 sparkplugs ordered from Checker Auto. About $6.95 each, I'd read about them and am always suspicious of their speil about increased gas milage, but so did all of the above mentioned. They do work. I got 3-5 mpg better. Might give them a try and see what they do for you!
Flying L