Catalytic converter cleaning instructions needed

Hello, I am Danny.

Well, sorry but there is no such option as "cleaning" a catalytic converter. Is there a diagnostic code reflecting the poor performance of the converter? It looks that your post states 900,000 miles on vehicle! As long as routine maintenance is performed vehicles can last a long time. Catalytic converters do require replacement after time and will usually set a diagnostic code (check engine light) when performance starts to suffer. Have you had a tune-up done recently? Is the check engine light on? Hope this helps.
Danny-