Given the state of manufacturing today and the (lack of) quality control, I'd not bet ANY new part was either to spec or not defective.
Idle control valve induced stalling can be the OVP letting the supply current wobble or leaking control valve hoses. They get hard and shrink, then expand when warm and get loose on the valve, so you get intermittant large vac leaks. This will cause lean running as the air isn't going past the air flow sensor, the EHA current will go up as the o2 sensor sees lean condition, but you will probably stall due to the time lag on the O2 sensor at idle.
Check those hoses, and all the rest too -- a bad vac line will cause lean running and stalling problems at idle.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!