1992 300SE has a M104.990 engine with LH fuel injection & EZL ignition(cap & rotor).

On that car fuel volume & air mass are the 2 keys for proper acceleration.
The fuel system should have 3.8-4.0bar of pressure UNDER acceleration. Also the pump should deliver 1 liter of fuel in under 25 seconds.
If that checks out then a exhaust pressure test (less than 1 psi at idle) measured at the O2 sensor hole would be the next test.
If that checks out..then either a replacement air mass sensor OR inspection of the timing chain condition.

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