Ok, so I jacked my car up because I was hearing a rattling noise and I saw my cat was discolored and if I bang on it I could hear all sorts of loose crap inside. Ever since my car does not pull as hard in first as it use to from a stop. Could this easly be the problem do to exhaust being blocked? or is it something else?

 

Yes, it could. If it's dying, you may as well remove it and knock the insides out completely or replace it.

 

As ricey said, if the catalyst is moving around inside the housing, you will have to replace the convertor.

 

just take it off and gut the hell out of it. it will give you more power than before even though you prolly wont feel it.