what is your reception like? is it up and down, my work is right on the edge of a cell and my reception is never a constant, right now there is a van parked out the window and I have no reception at all! if I set it to 3g and had it checking emails every 15 minutes my phone wouldn't last long, perhaps a working day i.e 8 hours but not 2...

Maybe your reception has dropped in your area? You could try autodisconnect and see if that helps, it will tell you if it's the traffic as it has a limiter i.e if less than x kb is downloaded in y minutes then disconnect.