My 2000 Sephia chugs at 25 & 45 mph approx. 2000 rpm if i push CEL flashes let off gas stops flashing. Have to very gradually put pressure on gas pedal til 30 & 50 mph then its fine. CEL showed many misfires so replaced plugs and wires and it ran better than ever for 4 days now doing same thing bought fuel filter but unsure if i can change. i have worked on cars older than 1980 and changed fuel filters in them ( being ford, dodge, chevy, one toyota ), however someone told me there is something different about this car. I know the filter looks dif. its larger and has three opening rather than the two in & out openings of old fuel filters. a mechanic said he would charge $20 to install but i have limited funds and if i can do it i'd like to save $29 for gas since i travel over 25mile radius for work. please give me an honest opinion because being a female I hear alot of bullshit from others when it comes to car repairs!