2003 ls v8 engine light

The wifes 03 lincoln ls threw a code today so i take it to autozone to get the code. They give me the code which is p0420 and a little slip of paper with about 11 makes with one being just domestic. The guy tells me some crap about catalysts an s--t. Also there is 4 possible reasons on my paper; catalytic converter failure, engine misfire or running condition, large vacuum leak, and engine oil leakage into exhaust valve guide seals and piston rings, im posting from my iphone in peppers so sorry about the grammar. Thanks for any help or advice

Welcome to the forum!

Have you tried searching the forum for P0420?

-Rod