Originally Posted by studlee
Whistling noise is a pretty good indicator or vacuum leak, or a hose leaking somewhere, either torn or pulled off.
Idle the engine and have a friend give throttle on off and listen for where it may be coming from. It might be as simple as the poster who just had to put the hose back on.
If not, then it'll need diagnostic.
I had a different car quite a few years back that developed an intake manifold gasket leak and the idle wouldn't calm down.
My buddy and I tracked it down with some propane gas and rubber hose.
We gave light gas from the hose and moved it around the intake parts until the idle changed. At the intake gasket, when the propane went through the gasket the idle went up. The gasket was bad on a relatively low mileage car (under 50k). It was a turbo 2.0 Mits engine.