Volvo 850 T-5 making a weird noise

[Chrisg13]

My 1997 Volvo 850 T-5 makes this noise when I'm driving and come to a complete stop and hold down the break. If I put it in neutral the noise stops and when I put it back into drive; the noise starts again. I just recently changed the pcv system so I can't be that, but I can't figure what it is.

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