My alternator problems are driving me crazy! Please some help here.

Last January I had the alternator in my 97 SC-2 changed. The reason
for the change was that the ABS light kept coming on. I was advised
from this group that the reason for this light coming on was that the
alternator was going bad and not putting out enough power for the ABS
system.
So even though the alternator tested ok, I had the alternator changed.
Things have been going ok for a few months but then, about a month
ago, the ABS light started coming on, usually but not always when the
a/c was engaged. Also I noticed that the Dash lights were flickering
slightly.

So back to machanic I went. Of course the alternator tested ok, but
since the alternator was still under warrenty(one year for a factory
rebuilt) my guy put a new alternator in yesterday.

Driving on the highway last night with headlights and a/c going the
alt light flickered momentarily and then the ABS light came on. This
was unusual because the
ABS light almost always came on right after the ABS system tested
itself at 8mph, usually with the a/c running.

In anycase, I've got this new alternator in. It couldn't have gone bad
so fast, could it? Is there anything that we are overlooking that
could cause the alternator to under power the car. Should my guy be
checking for bad wiring or something like that?

This makes it the car's forth alternator. The original one was
changed in Oct. 03. Then in Jan 04 after the ABS light started coming
on. And now yesterday.
This is not normal. The Battery is about 3 months old. What gives?

Thanks in advance for any help.