The whistling 20V, a story for which the world is not yet prepared.

[TWFAUST at aol.com]

Yesterday I posted about the 20V that followed me home. It turned out that, 
along with various tropical diseases previously unknown to science, it had a 
difficult time falling to idle and "whistled". I ran a highly concentrated dose 
of Techron, the "universal solvent", through it.

I received several suggestions from the list and had a few moments to look 
into it today. I noticed that when I "pulled the plug" on the ISV, idle speed 
didn't change and the "whistle" went away.
This suggests that the ISV is at least partly the culprit, or is it "perp" 
these days?

Several of the maladies I described have gone away. Such as the dieseling and 
the slow fall back to idle. It still idles at 1100.

There is still no change in idle speed if I open the oil fill cap. This 
suggests a vacuum leak. Can anyone suggest a method of isolating the leak?
P.S. The car is not a 20V 200, as some thought, it is a '91 90 20VQ.
Tom Faust