2002 Chevy Astro Van: The check engine light came on and Autozone told me it was the catalytic converter.?

A catalytic converter code is only po420 or po430 catalyst insufficiency. I dont know what code they pulled, I mean you went to a place to get a free diagnosis by an 8.00 an hour code reader that is not a diagnostician. The codes you say misfire, vacuum leak, engine oil leak (never in my life I have heard of that triggering a code) are generic. Good luck with the autozone diag.