Flushed with success!

Thanks for the info J!  I backflushed the heater, first with about 20 psi
air from my compressor, and then with flow from a garden hose for about 10
minutes.  Hooking things back up, I was immediately rewarded with copious
waves of HOT air from the  system, like I've never had since new.  I'll bet
that I was losing heater flow long before the Stop Leak shut things down
even further!

Details for other 96-97 vintage Taurus owners:

Make sure you BACK-flush (i.e have the flushing flow go in reverse of normal
to break crud loose, rather than drive it in further with a forward flush)
as described below.  Your system has been trying to forward flush  without
success for as long as you have had your problem!

I disconnected the heater by removing the short hose going from the hard
pipe on the right side of the firewall (normal return to y-pipe) at water
pump suction, and by disconnecting the short hose from the other "y-pipe" at
the left side of the firewall at the supply end.  (The y pipes provide the
connection points for the heater bypass hose.  I think the y-pipes and the
bypass hose were part of a recall mod made shortly after I bought the car.)

Hooked up a short garden hose section with the female end connector to the
heater return side hard pipe on the right fireall.  Positioned the short
section of hose still connected to the heater supply end hard pipe on the
left side of the firewall so it's discharge when back-flushing wouldnt get
into the transmssion fluid dipstick pipe.

Made up an adapter with a short section of garden hose with the male
connector to connect up my air line to the garden hose section on the heater
return pipe.  Set the compressor regulator to about 20 psi to prevent
overpressurizing the heater core in case it was REALLY clogged up.

Blowing down with air blew out a big slug of nasty looking stuff and rusty
coolant.  After a few minutes of air purge, switched over to a water purge
for about five minutes, using a local ball valve to throttle the water
supply to keep the pressure down.  Water discharging was clear throughout
the flush.

Removed the backflush adapter, restored the hose connections with new
stainless hose clamps, and topped off the expansion tank (since I was
working on high points of the system, I didn't fully drain the whole system
beforehand, and only lost a small amount of coolant when initially breaking
the connections).

As soon as the system warmed up after starting the engine, WOW!  Heat
blasting from the vents!   SUCCESS!   Unbelieveable what a small amount of
crud it takes to foul a heater core.

Wonder what the local Ford Dealer would have raped me for to correct this?
Probably would have tried to sell me a new core and the associated major
labor to tear the dash apart.  Here's hoping that the core doesn't develop
leaks....

Is that 12 beers total ????????