A clogged cat. converter or restricted exhaust can give these symptoms. When the car is cold, grab the converter and give it a shake. If you hear any rattling, you've found your problem....the ceramic monolith inside is breaking up and restricting exhaust.

Beyond that it could be something like a weak fuel pump, clogged sock filter in the tank, or something else with the fuel delivery system.

Or perhaps the ignition timing or valve timing is off.

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95 E320 Cabriolet, 169K