Car keeps shutting down?

My son's car shut off on him and wouldn't restart. It sounded like the battery was drained, so I replaced it. That didn't work, so I put the old one back in and I had AutoZone run a diagnostic. They said it was the BCM, knock sensor, alternator and starter. I changed the alternator and starter and then got the "service battery charging system" and the code for the crankshaft position sensor. Still getting the same message and now a code for the camshaft sensor. The car is still shutting off every so often, but I don't want to keep changing random parts that aren't fixing the issue.