Do a search on emissions failures. 60s usually seem to fail for high CO. In my experience, its frequently do do a weak or malfunctioning Air injection system. This includes the cat. The problem is, if the cat isn't getting enough fresh air from the air pump or ait switching valves, it can't do its job. The Toyota emmisions book is a must have if you plan to do any of the troubleshooting yourself. If not, find someone local who is familiar with FJ60s. Randomly replacing parts without a proper diognosis is expensive and likely won't fix it. You might have a carb problem but until you sure everthing else is working, I woouldn't make that leap.