It's rare for a cat. convertor to fail so soon. And even if it was the cat going, the ECU should set off a check engine light to tell you. I'd check for vacuum leaks first and then have a good look at the air mass meter. My '95 850 turbo failed emissions not too long ago and it was traced back to a faulty air mass meter. But check for the leaks first before touching the air mass meter because a new one isn't cheap. I've also heard that you can clean the sensor in the meter and sometimes that will be enough to get it working properly again.