My 2000 Impala runs great until infrequently when you shut it off it won't restart After waiting 30 minutes to 1 hour it restarts and runs great until the next time could it be crank shaft sensor?

Probably not. Usually it's caused when fuel leaks past a dirty injector and floods the engine. Before spending a lot of money, try adding injector cleaner with each of the next couple fill-ups. or you may check if the fuel pump is ok or not. Three reasons why an engine would be hard to start when hot: (1)Air filter clogged; (2)Fault in the fuel or electrical systems; (3)Fuel not reaching the injectors.