Manifold Vacuum and Smoke

[allenmengr]

There is no where else to put this question, so I put it here. Had a strange problem that went away. Rough idle and smoke at the back side of the engine on the passenger side. Also, power brakes, don't have power. Obvious thing is a manifold vacuum leak, but I can't figure out how it could be related to smoke(oil,transfluid,brake fluid, power steering fluid on the exhaust pipe? who knows?). I inspected all manifold vacuum lines and then verified good vacuum to the power assist module on the fire wall. then I replaced that hose and restarted the car. The problem went away and so did the smoke, but I don't know why. Any ideas? How is the smoke related to the other symtoms? Please read carefully all the symtoms.