94 Town Car heater problem

I sure hope someone can help, I have a 1994 Town Car with a heater problem. The cooling system has been flushed/backflushed, thermostat changed to a 195 from a 160 and the heater still blows cool air when requesting HOT. The heater goes to full hot when parked indoors but turns cool within 5 minutes of driving in minus 12 degrees. I have installed a rad blancket, this is a new problem for this car.

Feel the two radiator hoses for this vehicle. Are they both hot if both of them are hot they have a damper with a vacuum valve which opens the damper for heat. If you have climate control it may be somewhat different.
http://www.alldata.com sells an annual subscription for $25.00 which will cover this item. Lincolns online also has some data.
The older cars had a vacuum operated valve in the heater hose which shut off flow. I don't think your year has one but you can quickly check.
Look at the Mercury Grand Marquis forum for heater core replacement. They have a link with pictures the heater system is very close to a lincolns.

-- The heater goes to full hot when parked indoors but turns cool within 5 minutes of driving in minus 12 degrees. --

It's quite possible that the cooler airflow while driving is coincidental..

A broken Blend Door Actuator will show these symptoms too. The motions associated with driving, including airflow from the outside vent openings, can cause an uncontrolled Blend Door to open (allow cold air flow).

Another symptom of a broken Blend Door Actuator is the occasional 'banging' of the door as it flops around during vehicle motion.

Repair requires removing the dashboard panel just to get to the part.