First off, let me recommend an awesome article taken from the Honda OBD training manual, that does an excellent job explaining almost everything about how honda idle works: Honda IACV explained - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com

However, the one part that applies to me needed further elaboration, I was wondering if anyone could help me with this?

"23.7.2 Engine RPM "Dips" When a Load Event Occurs

If the RPM dips or bobbles when a certain load is introduced, it is probably not getting an "advanced warning" about the load. For instance, if every time you turn the steering wheel the idle fluctuates, the ECM is probably not getting a signal from the PSP switch."

This is exactly the problem I am having, but what can I check/replace to solve this problem? I have already swapped out the ECU with no change, and the wires leading to the IACV seem to be in good shape. Beyond that I dont know where to look.

 

before this I didnt realize I needed to unplug the IACV to correctly adjust the idle screw. When I unplug the connector, the idle shoots up to about 1500 and and cycles up and down by about 100 unless I turn the headlights on and hold down several window switches, at which point it idles steady at about 1500 even with the screw almost completely closed.

If the iacv is plugged in, the car idles steady at 700 with the idle screw about half open, unless I am stopped at a light. If i am stopped, sometimes but not all the time the idle will drop to around 500 or lower. Its stalled out on 3 occasions.

I have cleaned the IACV with carb cleaner, and cleaned the MAP with sensor cleaner.
This problem has been going on for years, but over the last month the car stalled out a few times which never happened before.

 

Which 2000 model do you have? Three wire IACVs must not be unplugged to adjust. Two-wire ones have a spring to close them when disconnected but the 3-wire has "open" and "close" wires and will be in an indeterminate position when unplugged.

I think the adjustment of a 3-wire system would be to leave it plugged in, and open the screw as far as possible to have idle under control with minimum load (automatic transmission in park or neutral, all accessories off, radiator fan not running).

 

yeah, I have 3 wire so that makes sense why it ran weird unplugged.