[suprra_girl]

i would suggest you get a new thermostat and install it.... with no thermostat the water is not staying in the radiator very long and getting a chance to cool... so effectively all you are doing is constantly running hot water thru your engine

the dash temp sensor is located on the side of the thermostat housing and has a spade terminal connection
i believe it is the bottom most sensor which is inside the power steering bracket, not the plug that is two pin and usually green, it's the one above that, make sure the terminal is on properly or even on at all

let us know how you get on