Fuel bleed off is a common problem that will cause this type of symptom. The only thing in the fuel pressure system that you haven't replaced is the fuel pressure regulator. However I would suggest that you have the fuel pressure tested to see whether the fuel pressure does bleed off when the car is shut off.
Many times a weak coil OR bad cap & rotor can cause the exact problem.

__________________
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)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator