Help intake manifold.

I just installed a Trick Flow street intake manifold. After test driving it when I put the car into nuetral I hear a whistling sound. So after tracing the sound I figured it's coming from somewhere around the upper intake. The thing that I dont understand and maybe you can help diagnose the problem is, when I disconnect the idle speed control solenoid the whistling starts up, then when I put it back, it stops. Whats the problem.
:screwy:
Thx for help.

Just for anyone that has a similar problem I called trick flow, they said that if you use a BBK throttle body there is a little hole on the throttle plate which makes a whistling noise when the air is sucked in. I drilled the hole to make it a little bit bigger and the whistling went away.