Interesting problem with my 1998 SVT (2.5 Duratec - 5 Speed). There is a brand new thermostat (Autozone), coolant temp sensor, temp switch, water pump, and cooling fan relays (both), however, the care overheats with the thermostat in. when I remove the thermostat, the engine overheats in traffic. The electric fans dont switch on when the temp of the coolant get high, so I wired in a switch. I was thinking that the hoses might be run incorectly as there was some backyard mechanic work done to it, but all the hoses are specific fit to their component making it impossible to put the wrong hose on the wrong part. Any help would be greatly appreciated. Thank you.