many thanks gents -- i have a few things to add---

-first, in the design of the idle valve it appears to me that there is a constant bypass (a small tube say about eighth inch in dia) that "short ciruits" air flow around the valve.
-second, I was absolutely astounded that the idle didnt rise when power way removed and now I think I understand that element.

another question -- in start up does the EHA determine fuel flow or is that determined by mechanical means until the lambda kicks in??

I will try the idea of taking the valve out of the equation and see what impact that has on idle.

Thanks much.