I keep watching the reruns that air at 3:30am here in Brooklyn on the WB network. The farthest I got up to was the episode where after 5 years they show clips from previous 5 years of Taxi. Was there a final episode after that, or is that the last episode that they showed?
Here is a summary of the last show produced:
http://www.tvtome.com/tvtome/servlet/GuidePageServlet/showid-14/epid-212/
There was another one shown after it.