2002 xg350 Low power possible fix

I found that the front or left (as they call it) catalytic converter on the bottom of the exhaust manifold had mostly burned up, due
to the engine misfire i had. About 3 inches of the honeycomb was missing in the bottom area of it.
I dumped out the remains from the exhaust pipe, which looked like gray rocks and powder.
What led me to this was code po431 coming on sometimes and the temperature of the pipe coming out of the converter
by the radiator was hotter than the back pipe because the exhaust couldn't get out.
Also my engine started leaking oil due to the pressure building up in the engine.
I ordered the part, i will let you know of the outcome.

P.S. I had to grind the rusty nuts off the exhaust pipe. The dealer had them.

 

It sounds like the cat is cooked. May be also clogged.
This will definitely mess with the engine
Oh, not unusual for rust to form on exhaust parts
It makes it almost impossible to fix exhaust.

 

CONFIRMED FIX:
Replaced the warm-up converter by the radiator.
Removed the pipe with the large converter on the back of it.
I held the front of the pipe down and lightly tapped on it to remove the particles(remains of the old warm-up converter).
This stuff must be removed from inside the pipe to regain the power of the engine.
P.S. If you remove the pipe under the warm-up converters, you can look in the bottom of them to see which
is missing material.