I was having a slight yet annoying idle problem. The engine would idle fine in park but when shifting into gear the idle would drop off significantly then recover. It just didn't seem quite right so I just couldn't leave it alone. I decide to clean the iac as per the faq destructions. While I was at it I cleaned the throttle body out as best I could without removing it. I also removed and cleaned up the grounds on the fuel rail. The idle is much better now. BUT now I have a very annoying hum. It is incredibly loud! I have gutted the aibox and when I cover the intake on the airbox, the sound is significantly reduced if not completely gone. When I unplug the iac the sound goes away but the engine dies shortly there after. I tried tapping on the iac with a wooden handle but nothing happens. Should have known not to screw with it when I have to go to work so soon! Any idears?

Oh yeah, It's a 91 745 b230f with the regina system.

Thanks, Marc