Why does my car shut down after a few minutes? on 1999 Buick Park Avenue

Already cleaned fuel filter, check lines, and a mechanic hook up to computer tester. Everything shows good. Previously disconnected door locks. Was told may need to decode the security system. How do I do that?

Asked by for the 1999 Buick Park Avenue
Undo your battery for about 5 mins then hook it back up it will reset