My guess and I am happy to be corrected, is that the hose is
carrying the MAP sensor signal. I have attached a couple of pics to explain...
On the AE111 the MAP signal is obtained via the grooves machined into the face
of the intake manifold. Each intake runner is sampled and the averaged signal
is ouput via the small spigit on top of the manifold (circled).
The spigot is then connected by a short hose to the pulsation damper, and from
there a longer hose connects to the MAP sensor. As I have never had a blacktop
and when I did have a manifold I didn't really take much notice of that hose,
I can't be 100% sure. Someone will need to confirm.