This problem is almost always related to the AIR FLOW POSITION SENSOR! There are many posts on this problem. BACK 10-12 years ago we replaced these sensors(with housing) on every car we sold!! Benzmac had that problem with his 16V as well.

$$$$ part & a pain to install MB number 000-074-23-14($720.)

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MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
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190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator