im driving a 98 civic lx... spark plugs, wires were changed about a year ago... i get a oil change every 4000 miles... i tried using fuel cleaner but hasnt helped a bit... my air intake filter is like 2 years old and never cleaned though but i doubt that kid be the reason im getting such low gas mileage... in florida i was averaging 250... now in nyc im averaging 100ish... what could be wrong?

 

change o2 sensor on the header and cat area...

 

you might be right... i remember changing my old o2 sensor but i exchanged it with a used one... loll will see if thats it...