Originally Posted by KhanTyranitar

Your assessment is incorrect. If the cat is glowing red hot, it means you have a misfire. Misfires allow both fuel an air to enter the vehicles exhaust. When the two combine in the converter, it will overheat the converter, causing it to glow red hot.

To say that the cat is plugged, causing it to glow red if the opposite of the reality. Whatever is causing (emphasis on CAUSING) the converter to glow red hot will cause the cat to plug up. The cat is not designed to operate that hot.



This statement is not entirely true. A rich condition alone will not overheat the cat, in fact it will cool it. The idea of creating a slightly rich condition to cool things down is not a new one, tuners have been doing since the invention of internal combustion. In order to overheat, there must be both excess fuel and oxygen.

Since you say the car is still sputtering, that leads me to believe that your misfire is still there.

Don't take me wrong, you converter is almost definitely bad, and would need to be replaced. But if you put a new converter on, and the sputtering misfire condition is not resolved, how long do you think your new converter will last?

Before you throw any more parts, you need to get this diagnosed. You need someone with a scan tool to find out what is wrong with your vehicle, someone who knows how to look beyond the codes. Looking at what you have done so far, you have not removed every possibility, hence the need for a proper diagnostic.