After 9 months of intermittent stalling when slowing down to a stop, or worse, stalling when slowing to go round corners, fixed the problem: cleaned idle control valve. Of course I found this solution by searching this forum. Car is 1985 MBZ 380SE. This was 6 weeks ago, hasn't stalled out since. I've also noticed the idle RPM now only drops to about 525 RPM when slowing down, it used to drop to about 400 before recovering.