Does the engine start faster if you hand prime after the stall? Could be sludge in the tank if the engine is starving fuel. Drain tank, pull screen and clean, rinse out and biocide tank.

Could be bad motor mounts. Motor racks and makes throttle cable hang.

Could be bad/dry bushings on the rotating firewall throttle rod.

If an oil bath air filter, you may have the oil level too high.

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daBenz - 1970 220D