I first read the codes and they came up 71, 72, 73, 74, 9, 68. I replaced Spark plugs/distributer cap and rotor, now it is only code 73 coming up. I check all the plugs again and all were white except for the 3rd which was dark brown. i swapped the third plug wire with a friends working plug wire. no change. It idles pretty rough, but drives fine. any suggestions what this could be? should i change the fuel filter? something to do with the catalytic converter? is it running to lean? vacuum leak? no sure where to go from here..

Cars & Trucks