1997 Honda Accord Idle sensor, Crankshaft! Oooommmmgg! Idk!

I will try to be brief. When I would put my car in park the idle would go up and down. Then, one day my car started acting like it was going to cut off! When it would do this as time past, I would just cut it off and start it back up and it would be fine. Somebody put it on a diagnostic machine it said, air valve system or something. They said change your air valve idle control sensor. I took it somewhere where else. They said the same thing. I changed the sensor. When I got the car back it drove fine but the idle would still go up and down when I put it in park. Then two days later the check engine light came back on and and it started acting like it's going to cut off again. This problem seems to happen mostly in the morning and it always seems to act like it's going to cut off at the same light as I'm going to work. Today, I can't deal. Today, my belts came off. I believe it's my alternator and a/c belts. They didn't break they just came off. This happened couple of years ago and somebody fixed it with something and told me to get part which is a little pin. I've had it for a couple of years. I had my car towed to a shop. He looked at it and said it's my crankshaft? And he's going to charge me $900! I cain't take it! I'm crying! Please help me!