Bad Water Pump?

I've got a '97 Ford Taurus. Lately the heater blows cold air and the the engine temperature spikes up to the point of over-heating. But it only does this when the engine is running say, below 1500 rpm. Above 1500 rpm everything is fine. The heat is hot and the engine temperature stays cool. My mechanic replaced the thermostat, flushed and filled the radiator and checked all my hoses, but the problem persists. What are we missing here?

Well it is probably one of two things:
1) The heater core may need to be backflushed.
2) the water pump is worn out.

I also have a 1997 ford taurus and I have been having a problem with it overheating. It is not consistent and does not happen everyday but when it does overheat and I stop the water overruns from the radiator jug on the side . Today I drove tha car several different places and nothing happened, it never ran hot and then I came home and left again and the first time I stopped and cut off the car water went everywhere out of the jug, it was super hot yet I didn't notice the needle going up. Why is this happening. I have had the thermostat changed and the radiator flushed.Also like the other person said,my heater does not seem to get hot. I notice that sometimes it blows heat but only for a minute. What is wrong?

Hey guys, I had the same exact problem with my Taurus, first I replaced the thermostat, that didnt work. So then i finally figured out it was the water pump, the bearing was fine but the fins were completely rusted off. You will be able to tell because the fan kicks in and its not leaking fluid but it overheats when it idles. so what you have to do is just replace your water pump. look at the coolant too, if theres a lot of rust in it that means its ur water pump.

If your taurus / sable / continental has a 3.8, likely it's a blown head gasket. Gasket leaks exhaust pressure into the cooling system creating an air lock. Air lock stops coolant from flowing through your heater core, and circulating through your radiator, which causes the engine to overheat. Upon reving the engine up, water pump circulates harder & coolant flows. However upon shut down, system is overpressured & may belch out coolant.