Suddenly my reliable euro 230E (W124, M102) began idleing low when starting. It used to idle at 1100 rpm in cold starts, and soon it fell to 750 rpm. That was what I considered normal.

But now it idles at a weak 500 - 550 rpm when it starts, and hesitates. After a moment however, idles at a normal 700 - 750 rpm. This happens specially when cold, and after the initial weakness the car runs and idles fine.

I suspected that the ICV was not providing the additional air the engine requires when starting cold, so I cleaned the ICV and applied directly 12v to it. It made a loud click, which I assume is indicating that it opens as it must be, and it leaves me without theory.

Can someone please suggest me what else to do to diagnose this problem?

Thanks for any advice.
Marcelo