okay, i just spent the last hour sifting through all the old threads to see if i can avoid asking this question. no luck. i have a 95 blazer w series with a 4.3 vortec. 2wd
i am sure that i have a vacuum issue. the line coming out of the firewall by the cruise control goes to a "T". From there the 6inch line on the left has a screw in it. the two foot line on the right is not plugged into anything. the vac ball has nothing going to it. cold air is coming from the floor and defrost vents only. which i am guessing is the default settings.
my question is, where exactly in the engine does the vac line plug in. and secondly, what is up with the small line with the screw in the end of it.
thanks in advance

 

i found where the vac line plugged into. the back top left of the engine. it just took awhile seeing that im not that mechanically inclined. also the diagram by 65longroof was helpful.
thanks for the help. next thing to is upgrade the fuel injectors. its running a little rich