OMG mike I can identify with this problem VERY WELL.
I gradually upgraded my intake and had to deal with this annoying whistling for about a year. I took Todd Z's advice and took some fine grit sandpaper to some of the sharp edges inside the TB. Its impossible to tell if what you've sanded down is going to make a difference until you put it all back together and go for a drive. I swear I took it apart, sanded a bit, put it back together and then drove it like 6 different times with minimal results every time. It was getting better little by little until I put a full intake kit and then it got LOUD.
I gave up monkeying around with it because I knew I wanted a Zabteck TB and I'd just wait till I got one. I was thinking it would be close to another year before I'd drive without hearing that god forsaken whistle, but a used Zabteck TB popped up on the S&S board and I jumped on it.
Now its all good
The Zabteck Throttle Body eliminated the whistle and gave the truck a whole new GROWL!
Thank god for Zabteck.
My advice to you, buy a new TB from Zabteck
If you can't afford that, get some fine grit sand paper and start going at that opening at the top of the TB that leads to the IAC. Sand down every sharp edge around the IAC and the TB you can feel with your finger,
BUT DONT SAND DOWN TOO MUCH - you dont want to $#@& anything up!
I think Todd can speak to this a bit better than I can, so shoot him an email or something. He's got a great picture of the area you should start by focusing on.
