2002 Ford Taurus O2 Sensors

If it was me, I would also perform a complete tune-up based on the mileage, which include spark plugs, all filters (air, cabin, fuel, and PCV). You should also clean the throttle body and use some injector cleaner.

Your O2 sensor is recommended replaced every 100K miles. You have 3 O2 sensors, but the ones that you need to replace are the one on the exhaust manifold. When you go to purchase, tell them the O2 sensor for the upstream/in front of the catalytic converter.

Cabin filter. As the name says, it filters the air going into the cabin. If it is dirty, it will make your A/C or heater works harder than it should (trying to push air through a clogged surface), reducing its efficiency and increasing the load to the engine, thus dropping your fuel economy. You will also breath "dirty" cabin compartment air.

Sorry to butt in and contradict, BUT.

Back in the early 1990s, Ford introduced new throttle bodies that are not to be cleaned. This had been a chronic problem with multi-point fuel injection through the 1980s. This was an effective cure. The throttle body has an internal coating that seals the outside diameter of the throttle plate. The throttle plate has a calibrated bleed hole in it to allow the proper airflow at idle to be maintained. Cleaning the throttle body removes this coating, and causes untold agony in trying to diagnose erratic idle, racing at stops, etc. NEVER - repeat NEVER clean a Ford throttle body!