Actually I have a 2002 ST and it's on the driver side.
Behind and down from the ignition coil, on the back of the valve cover, between the cover and firewall.
It has a u shaped metal tube bent around it with 2 coolant hoses (small) attached to the metal tube.
It's somewhat confined where the valve is. What I ended up doing was taking a screw driver between the valve and the metel U tube that surrounds it with the lines. I put enough pressure on the metal tube and broke of a bit of the plastic that hold the U tube within the valve that I was able to slip it over the valve. I then just twisted the valve off (it's a twist-lock type). The new valve (I got it via special order from Ford) comes with the metal U tube attached. I attached the lines to it then just twist locked the valve back in. I took me about 15 minutes doing it that way.