I had the same type of problem on my 190.
The fix for me was to take off the throttle position switch ( this gives a signel when the throttle is either open or closed).
It can be found in the front side of the throttle body and has 3 wires coming from it that go to the CIS module.
To check it disconnect the 3 pin connector at the front side of the CIS control valve/fuel distributor block and connect a DVM on ohms and you should have continuity accros 2 of the pins with the throttle closed and the other two when open, can't remember which pins but one pin is common an the other two are for open or closed.
If you cannot get continuity every time at open or closed then the switch is faulty.
The fix is to buy a new switch or fix the old one, it can be fixed by prying the top of housing off and cleaning the inside first then bend the copper strip that moves with the throttle shaft so that it will always touch the 2 contacts at either end of the housing, make sure that they are clean.
Chuck