When I first got the phone and was disappointed about the battery life (actually, I likely still am,) I tried turning everything off to see whether it made any real difference... NFC, no Wifi, Only Wifi etc. I concluded that nothing really made a big difference other than the Nokia Drive app. And note that I have Drive installed, but disabled as a background app.
My phone is currently set to 4G (fixed by AT&T), Wifi only when the phone is on, NFC on, location service on, Bluetooth is off though. I have 5 email accounts syncing and Twitter, Linked In.
Up to about 4 days ago the phone used to struggle to make it through a day and then it's suddenly doing much better.
At this point I would normally try and analyze what changed... but the evidence so far is that I've tried everything on this phone and it just has a mind of its own. If there is one thing that changed, and this may sounds far fetched, its that I used it quite a bit as a phone for a few days. It's mostly likely that this is nothing to do with the change and that today will be a bad day, but have you ever made some good telephone calls on the phone?