1998 ford taurus 3.0 24 valve DOHC charging dilema.

I have been fighting with this car for over a year. If I
wasn't so stubborn,  it would be at the bottom of
the CT river! The alternator chooses when it wants
to work. Or not work. I get the battery lighy on the
dash fir a second and then everything is great.
Drive for a while and the lights suddenly dim. Ut
will either start working again or drain the battery
down to nothing. It works very sporadically. I
changed the alternator and its connector. I have
12v at all times on one wire and 12 volts on the
other when the key is in the on position.  I have
read a million posts about this exact issue and
gave never seen one clear answer. I plan on trying
another alternator this weekend, vut the one in it is
doing the same thing the last one did. Hoping to
get lucky. Has anyone solved this almost 20 year
old problem with certainty yet? Does it need to just
get 12v to both terminals with new wiring? Let me
know what you have tried and more importantly,
what you've found to be a problem as well as what
you ended up doing to fix it. I'm getting the gas can
and torch ready!!!