Mo, try Advanced Task Manager Free, set it on Regular Kill 1 minute intervals, seems to let my Galaxy s3 run a little longer. On my s4, it lets me finish full games with maybe one quit every 30 minutes or so. It definitely does something, because the s4 quits in a few minutes if I'm not running ATManager.
This advice is not sanctioned by Zup, it's just what is working for me. Sometimes.
Manfred