I can think of one other possible thing. Is the voltage regulator part of a the alternator or separate? I have heard before that many places will replace the alternator but not the voltage regulator if the voltage regulator is still working. Its either that or you do have a belt that is slipping for some reason. The tensioner is also a possible culprit. Try turning off all your electrical loads like cruise control, A/C, headlights, radio, interior lights, etc. If this helps your alternator could also have one or two diodes that are bad which is till enabling it to charge a little. This is not likely though as the alternator has been replaced. Check to see if your voltage regulator was replaced. Hope this helps.
