I am not at all familiar with Euro-spec M110 of that era, however, I would imagine that the auxiliary air slide (used for warm up) remained until the end of production. With that high of an idle I would suspect the “auxiliary air slide,” mounted to the side of the block under the intake manifold, is your culprit. It will have 2 rubber hoses attached to it. One hose draws air from the forward side of the throttle plate (between the CIS mixture assembly and the throttle plate) while the second hose routes the air to the under side of the throttle plate. A preset metered opening determines the idle speed; a larger opening = higher RPM’s, hence the increased idle during cold start/warm up. With the engine speed you are referring to I think I would look at this device should you discover it is fitted to your vehicle. I am almost certain it is even with my limited Euro-spec knowledge.