It sounds like a vacuum leak, and it's most likely a leak in the power brake booster. The booster can leak when you have your foot on the brake--as you likely would when you're sitting at a stop light--but then not leak (or leak less) when your foot is off the brake, as it would be going down the road.Here’s my 1st problem: Engine runs great, idols fine after it’s warmed up a bit but when you put in DRIVE it starts to shake, rattle and shimmy like something is loose. It’s not the motor supports. When you get the car going down the road it does fine.It’s only when I come to a stop that it shakes so bad, almost to the point of cutting off it’s so bad of a shake.
First check to make sure the bolt in the center of the clutch is good and tight. Seems like a simple thing, but you'd be surprised.2nd problem: Air conditioning is working and blows cool air. But when you engage it you see and hear the clutch running like it’s loose or out of balance. Makes a lot of noise like a bearing problem.