Cbbfan101

I have a 94 cobra and when i start the engine when its cold the cars fan comes on when it gets up to temp, it cools down and the fan goes off. It works fine untill i start driving once i get over somewhere around 30 the fan kicks off and never comes back on until i turn the car off and let it cool back down ??? i have no idea i replaced the fan, coolant temp switch, thermostat and i think thats it any ideas i would greatly appreciate it