I was wondering if anyone could give me some info about the secondary air pump and how important it is. I have a check engine light on that says it's bad and was wondering how important it is to replace and if not if there's something to do to get rid of it, thanks.

 

so every once in a while my car starts but doesn't idle and just dies, when it does this i can normally leave it for a little while then come back later and it starts fine, i just recently cleaned out the catalytic converter and my check engine light is no longer on, any ideas on what is wrong