I have the same problem with the wistle....its honestly driving me crazy and i am also considering selling my car. I believe it all started after i installed the new TB and plenum. At first i thought it was my clutch and TOB so i had everything replaced...and that didnt solve the problem. Soon enough im going to put the stock intake tube back, stock TB, and plenum to see if that helps. Hope you find your problem...so i can fix mine too!!!
It's all started after my cams install last year, after that I have change everything thinking it might help but didn't. Cannot find where it's comming from so if I get a good deal I will selll my car