It's your water pump. I just had this same problem two weeks ago with my Mystique. At around 60,000 miles the pump dies on these cars.
My temp gauge was higher then normal so I then checked under the hood. The engine felt cool to the touch and I thought this was really odd!
I then got back in the car and drove it about 2 miles. Another thing I noticed was the heater was not as hot as normal. I came to a stop and then noticed there was no heat and watched the Temp gauge plummet completely past the red mark. I freaked out!!!
Both fans were screaming!!!
I turned the car off because I knew this was not good. After calling AAA and having the car towed 41 miles to my Ford Dealership they explained what the problem was.
The Water Pump died... then the Thermostat decided to join it. It's a good thing I didn't drive it any further because of the damage which can occur to the heads. The Dealership replaced the Pump, Thermostat, Upper Radiator Hose and a heat sensor - No Charge to me!
Ford is aware the pumps on these cars suck (due to they made them from plastic) and will pay for all of this if you have a decent dealership that will work with you and your mileage is around the 60,000 mile range.
Oh, replace it with an "Aluminum Pump"... it'll last much longer.
Eurythmian
