Howling from 2.3

[P.L.A.N. - A.]

So, just picked up a '95, 2wd, 2.3, manual for commuting. When it warms up, it makes a varied howling noise from what sounds like under the valve cover. If I loosen the oil fill cap, it goes away. It is being created by excess vaccum in the valve cover but I don't know what to do to make it stop. I have not become all that familiar with the EGR stuff. Has anyone heard of this before? It only happens at an idle and a bit of throttle clears it then it comes back as soon as it idles again.

I have read a bit about a vaccum cleaner noise from the air intake, but this isn't the same thing I don't think.

Any help would be appreciated.

 

[97ranger xlt]

wild guess but did you check the hose from the valve cover to the intake? also maybe check the pvc valve in case it's clogged up..