How does the 4age AFM system work?

[oldeskewltoy]

Although the cat may be old... and maybe tired... you have the right idea with checking the tune-up parts.

Replacing cap, rotor, wires, plugs, filters(air, fuel and oil) . I would also remove the grond connection on the battery while you do the tune up. this will make any "accidents" less likely to cause a problem, AND by disconnecting the batt you clear all codes.

Take it out after you get everything re-assembled, and the batt reconnected and drive it hard(3k+ rpm) for more than 15min and then take it to check emissions.

IF after the tune up the emissions are still high... then look @ replacing the cat.