Catalytic converter

If you look in to the CAT, you will see a lot of honey comb, if any of these is plugged up, the CAT is no good. The best way to tell if a CAT is plugged is when the car is running. With a vacuum gauge connected to manifold vacuum, check idle rpm, it should read about 19-20 inches of mercury, then run the engine at 3000, if the vacuum drops like 1 or more inches of mercury, then the CAT is most likely plugged. I know of NO way to clean a CAT, because when it plugs up, it is usually from being over heated and melting, often from a misfiring engine. Any blinking Check Engine Light? Because that is a warning that the engine is misfiring so severely that the CAT is being destroyed in the process