Can't comment on the MIL light strategy from the ECU. But this is very likely to be the Idle control valve. The good new is it's an easy fix and therefore worth checking first.
Pop the bonnet
Locate the throttle body/butterfly
Remove the throttle body
Remove the Idle Control Valve
add a little bit of a engine oil to the plunger of the control valve and reinstall
Basically, if it gets dry it struggles to move and can't respond fast enough when the engine speed drops, so the car stalls.
There's plenty of information about this, which I'll see if I can dig out.
http://www.saxperience.com/forum/sho...d.php?t=174710
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