Wow, first off, I can't believe that this post has been risen from the grave after two years!
But I suppose useful information never dies....
I reread all the posts here, looks like I never told everyone what happened.....
I finally went back to the dealer and yelled at them, about a week or so after I started this thread. The workers noticed that loose bolt and bracket too, and realized they did forget to put the vacuum reservoir there! So yes flanders20, your method did work:
why not take it back to the dealer and yell at them. should have been fixed right the first time. and tell them it wasnt doing it before
About a month later (yeah I guess ordering parts through snail-mail is slow, who knew....), they finally called me with the parts. They also gave me a diagram that shows how the vacuum lines are routed in that area. The hose in question (which prompted the starting of this thread) was shown connected to this reservoir, not to some $%^&* screw!
The reservoir is mounted in the same area that Scrat's picture shows above:
Needless to say, once they reinstalled the reservoir, the vents worked correctly! Quite an ordeal to get this problem solved, but I suppose it was worth it to finally have a working rig.
I'm not sure if that is the same part that I have in my truck. This search is for "1999 CHEVROLET S10 PICKUP Valve," so maybe the 1999 has a different part than my 2003.
I will look for the diagram and post it here if anyone is interested, just let me know. I may or may not have it still, I don't know where it went......