I was cleaning the battery cables on my 89 iroc and I noticed that there was obviosly something not connected. I've looked at vaccuum diagrams but I cant figure out where its supposed to go. Its and L98 V8 5.7 stock TPI. Its below the vaccum line on the bottom left side of the throttle body. (Looking at the car fron the front)

 

You talking about the alum tube underneath the TB behind the IAC motor ( the IAC shown circled in red )
or the bottom port on the TB itself ?

 

The one behind the iac,

 

It's the outlet of the throttle heater. Likely been bypassed, which is o.k.

 

Awesome thanks!

 

In the pic you can see a alum tube out the front next to the thermo housing.
Originally there were coolant hoses connected to both, is a popular mod to bypass the TB