same thing here, 03 XE I4 5 speed, it gets 20 mpg, don't matter hwy or city.
that's way off from the manfacutor rating.
I installed a cheap air/fuel ratio gauage.
that thing reads normal when I just start the engine,
then as the engine warm up it moves to too lean,
but anytime when the rpm goes higher then 3400,
it would just jump to too rich.
I have no clue, maybe the gauage isn't working well....