Same syptoms on a 190E 2.3 lead to the fuel pump relay. I would:
1. Check the idle control valve.
2. Check the fuel pump relay and filter.
3. Check the fuel pump.
1. Cap/Rotor and related components.
Investigate one thing at a time until your diagnosis is accurate. After elimanting those things, then further work will be needed if not solved.
1998 C230 "Black Betty"