Take an engine stethoscope to it. It is nearly IMPOSSIBLE to diagnose things over the 'net, especially an engine we are not experts at.

My thought would be it's time to change the timing belt and you are hearing the tensioner go bye-bye. But, once again, I ain't there to listen!

I have heard that on a 98 Contour....the belt was cracked on it, too, but since it is a non-interference engine, you'd only be stranded if it broke....some kind of relief, I guess.