SAAB 2001 shuts down in “midflight”

My 2001 SAAB 9.5 shuts down in the middle of driving….we have changed the alternator and battery because it did not want to start…and needed jumped all the time….now, if it feels like it, it will start, but after driving it for a while, all the dashboard lights turn on, and it just shuts off in the middle of driving….if it sits a couple hours, it will start back up again…sometimes when the key is turned, it just ticks, ticcks, ticks…..sometimes it will start…..HELP !!!! could the relay box be causing this problem?