5KCSTQ Rubber cap with slit, leak or not?

[Louis A. Mulieri]

Hi,
	I just noticed what might be a leaking capped metal tube
sticking upward just above and behind the throttle butterfly housing on my
88' 5KCSTQ. The metal tube is silver colored about 5/16 - 3/8" diameter
and the upward bent portion is about 1" long. The end of this tube is
blocked off by a light grey rubber, tophat-like cap held on by a
clamp. The side of this cap has a 1/8" slit in it through which I can feel
a small flow of pressured air escaping while the engine is running. There
is a carbon residue deposit around the edges of this slit suggesting the
air may be exhaust gas? What is this tube/cap and what is it supposed to
be doing. Should the cap have a slit in it? Thanks for some tutoring here.

Lou