Sorry, after all that, I missed that you had said you'd already replaced the alternator. For starters (no pun intended), I'd get the supplier (if local) or AutoZone or someone to test the alternator and the battery. This does sound like a weird problem if it persists after replacing the alternator - beyond my limited knowledge. Seems like normal problems would cause you to loose voltage,not increase it. The only other thing is that, though unlikely, the new alternator may have been defective off the shelf. Was it new or used? Did it come with a regulator - or perhaps did you put the old regulator on the new alternator? Let us know what you find out.

Regards, Calvin