I recieved a lot of help from (BabyHuey?) last month regarding a misfire and a possible cat problem. I replaced my plugs and it fixed it for awhile, but the problem is now back and I need help. I am going to take it into the shop on Wednesday and want to know some things before I do.

How difficult would it be to replace the cat (front or back) on my 2002 Protege 5? Can I use a Universal cat or should I only use the factory part for this? Is it possible that if I replace my cat that it is something else and that my cat will brea/go bad again soon? If i replace my cat should I be replacing anything wlse with it to ensure a top quality repair?

If you have any input for me I would greatly appreciate it.