Throttle valve or CC linkage. The throttle valve is buried pretty deep on the KE M103, under the flap for the fuel distributor. There has to be some room there between them, or the fuel flap will vibrate badly at some rpm ranges.
CC actuator is on the side of the engine, at the rear.
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!