OVP relay -- when it's intermittant, it causes the current to the idle control valve to drop, this drops the rpm to the point where the engine won't run properly, and it stalls. Can cause hard hot starts, too.
The same thing happens to the EHA, too, dropping the current to 0 at the wrong time, so you don't get the enrichment you need to accelerate. Just like a bad accelerator pump on a carb.
I'd replace the OVP relay before doing anything else, particularly if the ABS light flickers (same relay problem, different circuit in the relay).
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!