Yep - may battery drain and crashes have stopped. Overall, I turned off location services and simplied email by following the guidlines here: http://www.care4pcs.co.uk/2012/10/how-to-be-happy-gmail-user-on-iphone-or.html turning off push and switching to fetch every 30 minutes.
I final piece for me in the jigsaw following on from this
is to turn off wifi when you do not need it. When I leave the house I turn off wifi, because the majority of the times when my iPhone has got very hot and crashed is when I am away from home. I suspect that if the iPhone is in the vicinity of public wifi (wheather secure or not secure) it will try and connect, even if you have 'automatically join known networks' set to off. This is easy of course if you have an unlimited data contract for your iPhone. I may be wrong, but it is working for me. It makes sense for me because it is another way of reducing the work the processor (and battery) has to do and therefore reduces the chance of overheating.
Having said that, I never had this problem with my iPhone 4. I now have a 4S.
Try it. Hope it works for you.