head gasket problems?

^^^^^ clogged cat, at least the one attached to the exhaust mani cause the other one was stopped up when i had my exhaust put on, i left the one on the mani and shouldn't have, it is what cause my motor to go...........

so theres 2 cats?

Yea, One right off the stock Exhaust manifold and one further down the downpipe before the muffler...

so how would I tell which one is plugged? Also if I get a new cat installed should I do a O2 sensor the same time?

Take it apart and see if u can see sunlight threw them, lol. There real easy to knock out the insides if u dont have emission testings...

YEAH REPLACE THE O2 SENSOR IF YOU STILL HAVE ALL THE
EMISSIONS STUFF HOOKED UP. I WOULD DO AWAY WITH
BOTH CATS, AND JUST RUN ONE, YOU CAN GET A HIGH FLO
2" PACESETTER CAT FROM IMPORTPERFOMANCE.NET FOR
@$110 SHIPPED...LOOK AROUND YOU MIGHT FIND ONE CHEAPER....