Vacuum help please....

One day it's driving great the next day its:

Sputtering
Strong gas fumes
Poor brakeing
AC/Heat only comes out the top defroster vents
AC condensor clutch won't engage - I think that has been the case for a while...

So I understand the concept of a vacuum system but I'm having trouble understanding how it works exactly...

A) The ball under the hood won't hold a vacuum...
B) The hose that runs way down the back of the motor holds vacuum
C) The hose that goes into the back of the intake manifold appears to pull vacuum and goes into a black/clear connector which then goes to the ball (A) and the hose (B) and also plugs into a really small plastic hose going down the drivers side rear corner of the engine compartment and it won't hold a vacuum or pull a vacuum.

I'm not sure what the hose going into the throttle body should be doing but it goes into a couple modules and then to the back of the motor..

I've disconnected all the hoses at some point and don't get much change in the way the car runs. When I disconnect the hose going to the back of the intake manifold the rpms increase but the engine is still really loud/sputtering

Anyone have a drawing of what should be sucking and what fitings/connectors should be in place? That nice drawing GM supplied in the engine bay isn't helping me too much...

you dont say what year but if it is a 95 and older it is probably a stuck egr valve or cracked fuel lines or a leaking regulator inside the intake. take it to a dealer. it will be cheaper in the long run

you dont say what year but if it is a 95 and older it is probably a stuck egr valve or cracked fuel lines or a leaking regulator inside the intake. take it to a dealer. it will be cheaper in the long run
It's a 95 4wd Blazer. I took it to a shop this morning and they said it's a bad EGR $225 plus labor.....I think I'll try cleaning it first ;-)
Thanks