Stock 99 XJ, pretty bad fuel mileage

I am posting this for a friend.

Jjeep is a 1999 cherokee sport with 76 some odd thousand miles on it. and it gets only 13 mpg. its stock, and its gotten a tune up ,and changed the o2 sensors upon advice, and nothings gotten better. any ideas, because she doesnt want to lift this thing and get worse gas mileage.

4.0/AW4/3.55s

Check PSI in all tires. At stock height, I got pretty decent (17-18mpg city, 19-20 highway) running about 35psi with 235's on.

If you've already done a good tune up (assuming plugs, wires, cap and rotor) with quality parts, I would dump a can of good fuel injector cleaner in the next tank. Chevron Techron is a good one for not much money. Or about half a can of Seafoam added to the tank (with the rest added to the intake) works too.

Other than that, tell her to keep out of the skinny pedal. If she does a lot of short distance driving, thats the big killer on fuel economy.

Also consider running better quality gas, rather than going for what ever is cheapest at the time. I always get my best results running BP regular.

I second the PSI and the fuel system cleaner......works for me........i also drive like an old coot.......take off slow, drive steady, coast when you can.......i actually drive like they tell you to do here up north in the winter when youre a younger buck......" drive like theres an egg under the gas pedal " the less you push down on the gas pedal, the better MPG youll get, in theory.......i drive like that all the time on-road........the extra MPG gets wasted off road when i drive like a 16 year old kid with a 12 pack in him, and a stolen Jeep......drive it hard, or youll lose it, lol.......

I got a 98 stocker with the trip computer at it always says 13mpg even after a tank fill and reset. I am starting to wonder if it is broke. Drive it hard, drive it like an old lady, doesn't matter 13mpg.

Test, or have tested, the MAP sensor.