If the catalytic converter is plugged up; it would have to be replaced. But a clogged converter doesn't usually glow red; and if it was clogged, it would make the car lose power all the time, not just sometimes. What you describe sounds more like the fuel mixture has gone too rich. When that happens; the converter will get very hot because of all the excess fuel that is being burned inside it. This is usually caused by a fuel pressure regulator which has a leaking diaphragm. There is a rubber vacuum hose which attaches to the fuel pressure regulator. If you disconnect that hose, and it has fuel in it; the regulator diaphragm is bad. In that case; the fuel pressure regulator must be replaced. That will make the converter run cooler.
For your information, catalytic converters are often replaced needlessly, because people don't understand how to test them. It is easy to check whether a converter is clogged; just stand behind the exhaust pipe and have someone in the car step hard on the accelerator (while the transmission is in Park). There should normally be a blast of exhaust pressure and an increase in sound from the pipe when the accelerator is pressed. If there is little or no change in sound or exhaust pressure; then the converter is probably plugged.