I swear I run into trouble in the most convenient of places. The Volvo Gods must be smiling down on me since I tend to get into trouble only always near home:

After a bout of spirited driving coming from the airport in my 740 Turbo, about 100 meters from my driveway, I start hearing an awful and unfamilar high pitched whine/wheeze (sounds like me when I had a chest infection when I give wheezy coughs) when I step on the accelerator. And I seem to lose power as I go up the gentle incline. About ten meters from my driveway the engine stalls completely. I immediately restart the engine and it's no go. I give it about 30 seconds rest before I try and again and the engine starts up.

When I pull into my parking spot, I pop up the hood with the engine still running and I hear a very loud hissing sound coming from the vicinity of the intake manifold, or near the throttle body.

I check for loose or broken vacuum lines and I don't see any. It's a loud hiss which seems to emanate from somewhere near the IAC valve - I can't be any more sure since the fan is pretty loud.

When I twist the accelerator to rev the engine I hear an awful racket as if something is hitting something.

So gentlemen, do you reckon it's a failed or clogged IAC valve or something worse?

[BTW: I did a search of the archives and some hissing issues near the intake manifold have been due to broken manifold gaskets. The intake manifold gasket on this car is pretty new - installed 1200kms ago.]