I had the same problems with mine up until about a week ago. I read an article that stated it wasn't the phones problem but a battery problem due to LG batteries having a bad batch and overall suck. I ordered a anker battery off of eBay and guess what? I have not had one single issue again for a week straight. Same rom and kernel as before. So to anyone having issues and are using the stock battery replace it with a non OEM brand.
Sent from my LG-P999 using xda premium
Sent from my amazing G2X running Bionic Reloaded v1.2.1