Besides failing a smog- can a bad catalytic converter cause an engine to falter and surge?

I own a 2002 Kia it recently failed a smog- first OBD- then later emmissions. It was brought to a dealer who did some "campiagn work". Once this was done the OBD passed but the emission failed. It also is now running rough and surges when gas is depressed before it first stutters. Someone siad it may be the catalytic converter. Ideas?|||YES IT CAN. If the cat clogs up, your engine can't exhail so that inturn cause the intake of air to be restricted. The cat has honey-coned passage and if they melt or come apart it stops the exhaust from flowing through it.|||answer one is correct but also your exhaust sensors will be reading a lot more soot in your exhaust and make the computer try to compensate by changing your fuel/air mix as you drive. Get a new cat. There are cheap ones available if you don't want to go to the dealer. Total cost about two hundred installed.