In my 3.2 liter M104 engine, the throttle actuator actually combines all of those functions into one part. I have held it in my hand. It sits under the intake manifold.
The earlier 300E's with the m103 engine do not have a throttle actuator. I don't know what it is called, but it is not called the "throttle actuator".
I was under the impression that M119 engines have the same (or similar) throttle actuator that M104 engines have, and I haven't changed my mind, (at least not yet).
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".