Try to give us a general area where you might hear the air blowing out, if its underneath your car, its probibly an exhust leak, and is pretty easy to fix. I know on my tour when I am at a low RPM and a push the accelerator down pretty hard the intake will take a huge gulp of air, and I will hear like vaccume suck air at the left front of the car. But thats only when I give it the gas. Its also possible that you need a new air filter, so take a look at that, they are only 5-10$ and take 5 minutes to change, so couldnt hurt to do anyways.
