2000 Ford Taurus Chirp at idle

If you check right over the spot where the engine and trans bolt up together, just under the wire harness, you will see a sensor with a three wire connector on it. This is the camshaft position sensor. The shaft that drives it is called a syncronizer. They both need to be replaced, as this is probably the source of your noise. Verify the source of the noise and have a professional tehnician perform the repair since it has to be timed using a special tool. If you have any other questions, feel free to ask.
Dave