Thanks again, I will leave the plenum repair for later, although it's a bit noisier than normal it doesn't bothers me at the moment but since I've replaced many things in less than a month it will seriously bother my pocket if you know what I mean. About the other sound it seems to be coming out from the steering pump, the sound can be heard for a brief moment when you put any gear other than P or N, stop at a red light or turn the steering wheel, I checked the oil and seems to be at the proper level, I will check back tomorrow when the engine is cold; in the meantime I have uploaded a video, you can listen to the sound in it:
Windstar weird sound
Thanks in advance for your help.