I changed almost everything , wires , plugs , coil , all filters . It idles a little rough . I also put in many doses of injector cleaner since i owned it . Just tonight i drove it and it meraculously perfomed perfectly . I need to change one or two other engine mounts because they have deteriated . I did change one . I cleaned the MAF . I also changed the rear struts , drums , shoes , wheel cylinders , pads , rotors , flex lines and so on . I believe the o2 sensor is original . the car has 231,000 Km .[/u][/url]LOWETGT said:Yes, you definitely have an O2 on that year, I wonder how old it is. They can lose performance, there are plenty of bad fuels out there and "normal" driving habits are killer on O2 sensors. If original, it would probably help in MPG. How old is fuel filter, unlikely to cause horrible mpg, but a clogging fuel filter puts unneeded stress/ work to the pump. How long since last basic tune-up? Idle ok? Automatic/ overdrive operating? Throw us some more details and we will try to narrow it down.