Sounds to me like it could be the power steering pump which is nestled in the vee of the engine or the idler pulley forthe serpentine belt. Ford's power steering pumps are always noisy. The idler pulley also makes the noise you describe when the bearings start to go. There's plenty of posts on this if you search using "idler pulley" or "power steering pump" as the search argument.

'99 Sport TropicGreen,Duratec, SVT exhaust, Brembo rotors, Ceramic pads, K&N filters(oil & air), Alpine CDM7874, Polk DB570 speakers front and rear. Fog light mod. 50% Formula One tint.