[98CiviCn00b]

here are some things that have helped me increase gas mileage.

new plugs, cap, rotor, spark plug wires, fuel filter.
change o2 sensor
change coolant temp sensor
valve adjustment
double check your timing

maybe run some injector cleaner or fuel system cleaner through the car

also is the car aligned correctly? improper alignment can lead to poor gas mileage.

Good advice im in the process of doing the same, atleast you dont have code 45 coming off and on like a phantom.