An engine will also stall when pushing in clutch if running too rich. Rpm's fall too fast past idle and do not recover quickly enough even with idle valve. Seen this many times when tuning an engine. May not be the issue in this case but just a consideration.

 

The oil analysis should help us sort if its related to thrust washer bearing.

But either way, you really need to fit a clutch interlock bypass, so car can be started without having to press clutch, which is where most of the wear comes from, especially when starting cold. No lube and high pressure on bearing.

A bypass can be as simple as a piece of wire or even a paper clip, or as sophisticated as a relay connected to brake pedal (so brake pedal acts as surrogate for pressing clutch, and provides nearly the same safety factor).

DIY for each if these scenarios and more can be found by searching.