I haven't elimiinated any of the above. I'm a bit of a newb, but I'm very capable of moderate repairs/maintenance.There are tons of things that can affect MPG. The state of maintenance on the engine in general, spark plugs, O2 sensors, catalytic converters, MAF sensor, clogged intake or throttle body. What possibilities have you eliminated?
What would you start with? At 96k miles I should start with plugs? If I remove the O2 sensors, can I visually inspect them for wear? What about the fuel injectors?