Ok, I know it is really an idle enrichment adjuster, but it is acting up nonetheless. The first notch does nothing, no change in idle speed, no affect on cold start. The second notch does work, and it hasn't been an issue until Saturday mornings 33-degree start, when I needed a little steady throttle to keep it going to warm up.
I did look into the throttle bodies and as I move it to the first notch I can see a linkage move, and again to the second notch it opens further.
Any ideas? Thanks folks!