[s-cars] Alternator problem - Help!

[J R]

I've got the battery light, brake light and ABS light lit on the dash
console.  At higher RPMs, those lights go out, only to come back on when
RPMs drop.  I'm only getting 7.2 volts at the back of the alternator at
idle.  Battery is putting out 12.2 solid.  I just had it rebuilt a few
months ago and it worked fine until now.  I replaced the serpentine belt and
tensioner (needed it anyway), thinking that maybe the belt was slipping.  No
change.  I just replaced the voltage regulator hoping for a cheap fix.
Again, no change.  Anyone have any ideas?