I had the same problem with my 92 V6. I was told by the emissions guys that Toyotas are NOTORIOUS for failing tests when they really have nothing wrong. The reason is that they take a while to heat up the CAT. So what happens is you take your car for a test, park it for 30 mins or more, and the CAT cools. Then they pull it in to test it and the CAT doesn't get enough time to get hot again, and it doesn't burn all the unused fuel, causing you to fail just as stated.
What I had to do is find a place that wasn't busy, (ask what time specifically) and drive long enough to get it good and hot, then make sure they get it right in when you arrive. I passed EASILY when this was done.
The worst part for me is that where I live, emissions were required every 3 years or something, and my third year came up at the end of 2006. Emissions requirements were removed as of 2007!!!!
