You didn't list the year of your 190e, so I will have to make some guesses as to the source of your problem.

If it had KE-Jetronic injection (cis -- no wires to the injectors, just solid metal lines from the fuel distributor under the air filter), you most likely have the idle/performace problems common to the 300e of similar age. These are OVP relay, idle mixture at the upper or lower limit of computer feedback control, or a bad, stuck, or leaking idle control valve.

The hoses on the idle control valve will cause air leaks, and you symptoms are just like that -- rough idle, random stalling while stopping, particularly on a hard stop, and terrible throttle lag -- you stand on in and NOTHING happens for several seconds, then the car takes off. Sometimes is will also stall. This is due to the large air leak at the idle control valve.

Other vacuum leaks will cause trouble, too, so check all the vac lines -- there is one to the computer on the fender, a transmission line, and lines to the EGR and some thermovalves. I'd replace all of them, they are likely dead. If the tranny shifts late and hard, this is more evidence of vac leaks. The only part you need to replace is the short rubber ends, the hard plastic will be OK unless broken, in which case a short rubber bit will patch it.

The OVP relay provides power for the electrohydraulic actuator on the back of the fuel distributor, and if it is bad, the EHA goes on and off randomly, doing strange things to the fuel mixture. Causes rough idle and throttle lag, sometimes.

If the idle speed control valve sticks, in will cause rough idle as it fails to respond to small changes in idle speed, then "jumps" and sticks again. It is closed above 1000 rpm or so with the throttle closed, and if it sticks shut, the engine will die it if doesn't jump open soon enough. Cure is to take it off and flush it well with carb cleaner, perferably while running the motor back and forth, until it works properly and there is no more discoloroation of the carb cleaner.

There are many posts on idle/preformance problems on 300Es -- your engine and control systems are similar.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!