Ive been struggling with this for a while and finally nailed down the problem. Mind you, this was what was doing it for me and might not be you problem if you are experiencing the same issues. Take it for what its worth. I usually run my phone with the wifi on to save on data (just because I live in Canada and we get raped for data charges). I found that if i have my Google Play app set to auto-update over wifi, the phone seems to hang when it tries to update my apps. It gets hot and the battery tanks. I simply switched the setting within the Play app to manual update and the phone has been working flawlessly. Ifyou are experiencing the same problems maybe try this. Maybe if I ever get upgraded to KITKAT it might solve the issue. Just throwing this out there and hope it helps.
Cheers!
Cheers!