For the past month I have had this faint noise coming from the dash. The best way to describe the sound is, a poker card inside the spokes of a bicycle. I hear it when I'm at a stoplight or stop sign. And it has a constant type rhythm and as soon as give the engine gas the sound speeds up very rapidly until I get to 10 MPH or so and stops. And then returns as soon as I start slowing down at 10-15 MPH to a complete stop. I thought it may have been a vacuum line sucking air. I did notice my power steering fluid being low. Do the think the reservoir is possibly sucking some air to do the power steering pump.

To top of the power steering reservoir is there any special fluid or just regular PS fluid. Thanks for any information on the dash noise if anyone has a diagnosis.