[cbreze]

Need to make sure your opera cache isn't getting to full. I have memmaid auto clean mine alot. Also prolly should be starting from a stock oem prior to a custom flash. Hard resetting before/after flashing. If you did this already then I dunno. I'd maybe go back to 6.1 oem and start over. Also look at stuff your installing, maybe something's sapping mem away after awhile. You didn't state if your losing program mem.
Just reread your post and see you didn't install any apps. Was the original rom (oem) like this? I'm back on 6.1 myself as it is such a stability/speed dream. I've tried almost all, yet end up back here everytime.