his signal reading is pretty weak. -120 i believe is like absolutely no signal just for reference. The fact that it's fluctuating like that reminds me of the issue I had where I had basically a 2 mile dead zone around my subdivision. Unless he has a bad radio I think the tower serving his area is out of alignment or something is wacky with it.
Have you traveled any distance from your house and seen if that made any difference? Just curious, some people work or go to school some distance away and that would put you on a new tower possibly. I've had zero issues myself with the rom so I don't know what to say. Either I'm lucky, or it's just your phone or I suspect it's a vzw tower issue though they won't admit it.
I'd try a reinstall one more time don't put an update over another just grab the full 5071 and wipe everything, data, cache, system, ... all of it. then install. If that doesn't work I don't know. Do you work some distance aways from your house? like 20-30 miles? You would have to travel far enough to jump to another tower if you want to see if that is the issue.