Good Lord I have never seen a drop that drastic. So wifi is not your only culprit. I am not rooted so am of no help with that or any ROMs that you run.
Question for all out there. Does anyone else notice a big difference between their ROM battery life and stock battery life? If I switch from my ROM to my stock there is about 30% more battery on my stock than my rom
So I think it might just be a bad battery. At least I've fixed it now so it doesn't drain too bad when the screen is off. I've had my phone on since yesterday morning, and its still at 18%. I've only had about 2 hours of screen on time though, so it probably isn't as good as it should be. I'll hopefully get a new battery in the next week or two.