Hamwich, look in "car builder solutions" on line and replace the whole in-line sensor housing and sensor as a starting point. The thermostat opened at 100'c you said.... mmmm, that is probably a little high! You will need to check but I have a feeling that it should be a thermostat that opens at either 85' or 90' c. that could explain you raised head temp on measuring. Is your engine still a CVH Ford and is it injection or carb fed. I'm sure there is a difference in thermostat opening temp however if you cant find the info out whip the stat out and it should have a temp setting on it, as it was working fine before a replacement should be ok. When the stat is out check it in a pan of water with a thermometer and see the true opening temp.
That's a quick answer but i'll read your tale more slowly later and try and get some better logic into it!
