Mystery hose 2000 oldsmobile silhouette premiere

I have a hose the is coming out of my air intake manifold hose and goes towards the rear of the engine. It is disconnected from whatever it was connected to.
It is plastic and about 1-1/2 to 2 foot long. It has a threaded coupling on the end that is disconnected. O.D. of hose is about 3/8" to 1/2"
Is This a Vacuum hose?
Where does the end with the coupling connect to?:jerking:

Its a breather hose, there is a rubber grommet under the coil mount bracket that goes into the valve cover, that where the "threaded" end goes, just pushes into the grommet.

Ahh, ok thanks. I'll take a look tomorrow.