franklin,
if u changed the thermostat and its housing the cause of the car overheating is probably the fan itself. Connect the fan to your battery (disconnect the fan motor's circutry from your car first) and see if it runs. If not the motor is probably burned. Replacing it isn't too difficult. If the fan does run check the voltage from the wires that supply power from you battery. If not that than check the voltage over the wires leading to and from the thermo. Good luck!