What's wrong with my car?
 

I have this problem with my car that when I'm at a stop and take my foot off the brake to hit the gas pedal the rev's will drop so low the car will shake and act like it's about to die. and when I finally hit the gas pedal the car will hesitate for a second before taking off

Every time I shut off my car I hear this big sucking sound and when it's driving at low speeds I can hear like a low pitched whistle.

Any help?

Sounds like your intake is leaking to me.