My geo metro starts up like a champ, at first she would hesitate at 35 miles and hour above or below that she did fine....Now tho, when I take her out she cant get past 15 miles an hour before she hesitates and when I try to reach speeds of over that it sounds like I have her in park and am gunning the engine....question, dirty fuel filter? or catylistic converter? otherwise she runs good. I already did the routine maintenence of plugs, wires, etc....any help would be appreciated