Rattle Noise at idle on 1999 Ford Windstar

I hear a rattle type noise at idle- seems to be coming from under the black plastic intake- the noise goes away on accel- i thought it sounded like a waterpump- but it seems to from under the intake-someone said there was a "balance shaft" that sometimes goes bad on theis engine. any ideas?

Asked by for the 1999 Ford Windstar
it is the older style 2 piece air has updated this part...
Is this a factory recall item?
1 more answer
sometimes the serpentine belt will make a noise that sounds like a rattle, with the engine off spray a little belt grip ( available at auto parts stores ) your vehicle also has a belt tensioner pulley and idler pulley that could be failing.