hello everyone,

i recently bought this 1984 trans am and right away fired it up, the car began to seriously shake, i thought the car might be warming up or just plain low idle, easy fix right? well over time the idle began to get really crazy, like starting it and it would be at 1,000 RPM or like today it would roughly be at 2,000 RPM. and every time the tachometer needle would bounce around slightly. to make matters worse one day i fired the engine up to try to see if the idle fixed itself and the car made a loud slapping sound, fearing for the engine i shut it down and opened the hood to discover the belt to the altinaitor had poped off and wrapped itself around the cooling pump fan! luckily i noticed no damage to the car, my fear was the crank shaft pulleys doing, (which has had a slight wobble since i got it and goes away when the engine revs higher) so now my fear is that there may be some serious damage caused by the harmonic balancer. so i wanted to know if 1 any one has had this problem with the shaking and the idle and how they fixed it. and 2 of any one knows how long the engine has to run with a bad harmonic balancer to do damage and f a dealer can fix it and for how much it usually costs to fix
i belive i have a 305 engine under the hood, and it has a carb intake and a water pump driven fan and a has a CEL

-Thanks guys for any help!