Two additional clues, the EHA valve has a slight leak in it. I noticed it looked wet, and wiped it dry. I drove around town, and it's wet again. Also, there is a switch triggered when the linkage returns to idle. I noticed that this wasn't being triggered by returned to idle. I cleaned the linkage, but this didn't help. I then added two more turns to the linkage cross piece, and now it's clinking when the linkage returns to idle.
This didn't change the current to the idle control valve with the ignition on and the engine not running (can't test fire this late at night, will trial it tomorrow), so I still think there's still something wrong.

Dave