why does car shut off after 45 seconds of idling?

Hello menefeehometown55ec96, This could be a problem with a vacuum leak in one of the smaller vacuum hoses of the engine, or it could be a failing of the idle air control valve, which could be dirty or simply malfunctioning. I would have both of those parts checked out. Let us know if their is anything else we can help with. RepairPal Oliver

This could also be an issue with your fuel system. My concern lies more with "waiting 45 minutes". Vacuum leaks typically don't require waiting -- they can be intermittent, but don't require waiting to restart. A proper diagnosis is required to find out what is going on with your air intake, fuel and exhaust systems -- could be even an exhaust restriction.