can you post the results of your failed AirCare test? if you were near max on all readings or failed almost all readings, then you probably need a new cat converter. if you did well on a lot of readings, and only failed one or two readings then you can find ways to "cheat" AirCare without buying a new cat converter.
if you need a new cat converter, buy a cheap one and have a muffler shop to weld/install it. I would recommend AMT machine shop, as the owner is very fairly priced. probably much cheaper than a regular muffler shop. he can help you to buy a new cat converter through Lordco (or other parts shop) as he gets a good discount.
AMT Machine Shop 604-251-3301