Your idle control valve is sticking closed, a very common problem on the CIS injection.
Clean it and check the condition of the associated hoses. If they are rock hard, replace them as they are leaking, making the problem worse by causing intermittant overlean mixture on coast, too.
Fuel pump relay or fuel pump will cause intermittant stalling at any speed or driving condition, not just on deceleration.
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!