high rpm

I post again a problem I have with my 91 old cutllas supreme 3.4. While the car is cold and the outside temperature is below 0 and I just turn the key on without starting the car the coolant fan motor start running (an indication that I will run in high rpm mode if I start the car). If I will go on to start the car the rpm goes very high, probably above 3000 rmp but the rpm on the dash shows zero rpm (the rpm indicator is dead in other words). I have to start the car 2 to 3 times before it gets in normal operation. Even when I stop for gas and I restart the car it will do this problem, and I have to start the car 2 3 times to make it run properly. Any help as to what part could be bad would be greatly appreciated. One mechanic said is the module, another said is the ecm another one said it is the coolant temperature sensor. Thank you.