It could be your throttle body. There was a member a while back that had the very same 'whistle' he described as you did to the T

He ended up installing a throttle body from another 3800 motor and it went away.

Yes, I do remember reading that a few months back. Wasn't it because it didn't line up right or something like that?

I should also mention I had a 2 new engines put in it for a total of 3 altogether, and it still does it...

Welcome our newest 3 Motor Club member!

Well than I would say it has to be one of your accessories your transferring over from all 3 motors. Your throttle body probably.

and your car is black to....huh

ok found the post
https://www.gmforum.com/t278613/

I know I know
3 posts in a row....

How much is a new TB? I don't really feel like paying for another repair after my side mirror...

4

https://www.gmforum.com/t278500/

It has to be the TB, because I have the new APN UIM, nothing wrong there!

you don't have to go new. hit up your local salvage yard for one and save money.