Verified answer

o2 sensor take it to the parts store and get them to read the codes but the o2 sensor is most likely.

rd

Well, it has 165K miles on it. Your car will never run as good as it did from the factory. No matter how well you maintain it, the years take their toll and parts of the engine inevitably wear, and the performance/economy is reduced. You could opt for an engine rebuild, a new engine, or a new car. There's not some fuel additive or bolt on part that is going to cause your economy to skyrocket. Now, if your economy has suddenly dropped by a couple miles a gallon, then you likely have something wrong with you engine. But, gradual loss over time is not a matter for concern, its just how physics works. Hope this helps.

Well, the spark plugs on this car are only meant to last 15,000 miles. Good chance those are still original and completely trashed by now. The two ignition wires should be replaced too if they are original. A plugged catalytic converter would be your next likely source. Anything else is going to cause the car to run crappy and trigger a check engine light - especially bad O2 sensors so you can ignore the first guy.

yeah it could use a good tune up. spark plugs, trans fluid service, air filter, fuel filter, injector cleaner. Yes, I also agree that the car could also use new o2 sensor, and a mass air flow sensor.

simplest things first

check air filter and tire pressures

those are dirty or low you get bad milage.

next check your driving. agressive driving will get worse mileage.

have you try ed changing the air filter

GET A BASIC TUNE UP AND IT WILL DO THE TRICK.