1999 Pontiac Grand Am steam

During inspection my mechanic said that I needed to replace the intake? - Something to do with the engine. Yesterday I saw steam and thought that it was caused by the rust protection. Today it was steaming much more and actually the low coolant light came on. In the morning things are fine, however on the way home, it acts up. I also observed that the overflow container has little bits of black stuff and I planned to clean it out in the spring. The cooling fan at 3 is very hot and blows hard and at 2 nothing happens. My question is, what is the proper diagnosis and estimated cost? Although made in the USA, this car is now in Canada. Would I have a great car for the winter? Thanks for your answer.