Due to tiny size of shaft and vents within this device, I reasoned that they could be clogged and causing my problem.

I cleaned my old ISC and took my car for a drive - no more idle problems.

I'll write up what I did and post a link. This forum has image limits that are too small.

http://philatwarrimoo.blogspot.com.au/2012/11/cleaning-and-idle-speed-control-valve.html