Throttle body cleaning and associated vacuum hoses location

[boxster_nut 1]

vintage 1997 Boxster....

Shortly after I changed the oil, the revolutions at idle began to oscillate between 300 rpm to about 1200 rpm.  Reading various forums identified the most common problem is a dirty throttle body, possibly the Oil Air Separator (OAS). Given the car has 34K miles and cleaning the TB has never been done, I figured it was time.  The throttle body was indeed filthy with a very light oil-like coating, and same for the plenum to the cylinders.  Having seen pictures of the effects of a bad oil separator, I figured mine was ok and what I observed was just buildup of 34K miles.

After a through cleaning I reassembled the TB and remounted it (what a PITA that was because each side of the 'T' plenum would not line up with their respective intake manifold).  What a struggle.

Finally got it beat into submission and connected the vacuum lines and this is where I need some help. Standing behind the engine, on the extreme RHS there is a vacuum line with what looks like a check valve that goes into the RHS plenum.  Got that inserted although is seems rather loose.

Now, on the LHS  at the rear, when I had removed the TB, I noticed a very small (less the 1/8" OD), thin black hose about 6" long that was adjacent to the hydraulic fluid reservoir - I don't recall if I pulled this out of the  'T' plenum or where is should be plugged.

Can anyone offer any suggestions?  Perhaps a drawing showing the vacuum lines attached the the TB plenum?

The car seems to run OK after the cleaning and I do not notice any  strange behavior.

Insight much appreciated.

John