I chased the heating issues too, but I am in nice warm/hot weather in southern california,where it is not uncommon in the summer to get to 100.
I was chasing a heating issue with my car for about 6 months after my engine swap and my UDP pulley from the SHOshop.
I did the following to "compensate for my heating issues"
Changed Radiator fans with high flowing 12 inch fans from perma-cool. pushes out more CFM.
Changed to a cooler thermostat to a 180. (if you guys know where we can get a 160 for the duratec let me know)
Changed all the hoses.(done at time of engine swap, this is expensive 600-700 bucks)
Changed temp sensor, overflow resivoir(had a small crack in it would only leak under high pressure), and the radiator/reservior cap.
I was running distilled water with redline in it.
I also was running a transcooler.
Even with all of these things my engine was running 1/2 way and then would climb up to 3/4 and if I was under heavy load with AC, uphill, and 4 people in the car it would try to creep up to the redline.
I was not happy with my cooling. My old engine with the transcooler hooked up independantly of the radiator(not in series) would run 1/4 and if it was really hot 1/2. My current heating issue I believe was attributed this to the UDP causing the water pump to spin slower and the new engine with much better compression thus producing more heat.
I was avoiding the obvoius(besides taking off the UDP), I neededto replace radiator. I had done recent flushes and it didn't seem to help that much. I know I didn't do a good job of flushing my system through the ownership of my car.
I even tried spraying my radiator with a high pressure nozzle to clean out any "gunk" in the fins. So I bit the bullet and decided to replace the radiator.
Some information for you taurus guys. The radiator is the same for all GL, duratec, and SHO models. It is a single core radiator. I hunted around because I wanted a dual core radiator, I could not find any. I could have had a special one made up but it would have cost around 500 dollers, and the space is pretty tight in there. You "could" squeeze a dual core in there but you would have to be careful.
Well I got a radiator from modine and spent the course of a week putting it in.
I also planned ahead and wanted to put in a oil cooler to help compensate for additional heating. Well I mounted the oil cooler but I have not hooked it up yet just becuase I wanted to put some better filtration on my oil, like a dual bypass oil filter.
After doing all this the engine runs at 1/4 on the highways and 1/2 in stop and go traffic. It can creep up a little past 1/2 but it is not that common.
The moral of the story is that after 190K miles if not sooner, its time to replace your radiator. I tried to avoid it but it does make a big difference. I accidently let my old one fall on its side and I was amazed on how much debris where in the fins even after hitting it with a high pressure nozzle(I think now the AC evaporator was deflecting the water from getting to the radiator). I have yet to crack it open and see if the radiator was gunked up inside.
Another side note I have noticed when the engine get hots like at the 1/2 mark the power seems to sag. When the engine is nice and cool It seems to have more kick to it. Could be a duratec thing. I'll keep you guys posted when I finally hook up my Oil Cooler. Hope this info is helpfull.
levi