I spent a couple hours searching but couldn't find a really clear answer, so I'm posting this up in hopes that someone can give me some specifics.

This is on a 87 non-turbo.

On the back of the upper intake manifold there's a row of three vacuum lines. I'm pretty sure the inner one (closest to driver's side) is for the automatic transmission, the middle one is for the cold-start thermowax. It's the outer (passenger side) line, which has an elbow so that it's pointing verticle, that I am wondering about.

Here's a pic: vacuum line

Basically I'm trying to get my car to pass emissions. It passed the tailpipe test easily, but failed due to bad idle and these vacuum lines. I've since replaced the TB (mine was modded), and am trying to replace all the proper vacuum lines that I can.

 

I belive that goes to the cruise control actuator.

 

Cap it off. I don't have it connected on my car either. But I also have ALOT of stuff removed that had vacuum lines...