Idle speed blues. Still need suggestions please.

["stevepeck1" <stevepeck1@xxxx>]

This week, I read in the archives that the three brass screws on the 
intake manifold are to be lightly seated. Did that, and the car now 
idles at 600RPM with no accessories on.

The idle motor seems to work. It vibrates with the engine off. I am 
unclear if it works when the engine is on, as it is difficult to tell 
if the vibrations come from it or the engine. When I unplug it with 
the engine running, there is no difference in the idle speed. When I 
plug it back in the idle speed changes for less than a second and 
returns to about 600.

The frequency valve on the right valve cover buzzes like an angry 
hornet, and the full throttle switch when pressed increases the idle 
about 50 RPM, so clearly it functions and the connections are good.

Begging for suggestions. I've searched the archive for HOURS!.

-Steve #3302