'96 C230K stalls when car comes to idle

Hi all,
Does anyone have know why my C230K stalls when I come to idle? For example while driving if I have to stop at traffic lights, round- abouts, etc and depress the clutch to change down gear, the engine
revs drop way down and more often than not the car stalls. It never use to do this and has been gradually getting worse over the last few weeks.
Thanks Colin
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Two possibilities come to mind:
A vacuum leak between the mass air sensor (MAS) and the intake manifold or a split vacuum hose that's attached (or should be) to the intake manifold. As the motor slows a small vacuum leak becomes proportionately greater to the air moving into the motor. Unmetered (leaking) air dilutes the air / fuel ratio so the motor will be underfueled and stumble. Idle the hot engine and listen for a hissing sound that indicates a vacuum leak. Check the clamp connections to the MAS and those rubber boots, also check the air duct's clamp to the intake manifold.
The second is the fuel pressure regulator, a small drum attached to the fuel rail to which the fuel injectors are attached. The regulator has a vacuum hose attached to it (hose's other end is attached to intake manifold). With engine OFF simply remove the rubber vacuum hose from the regulator; the regulator is defective if fuel drips from it.
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