Gasoline engines have throttle bodies since they operate at an air:fuel ratio of about 14.7:1. If the air intake in a spark ignition engine were not controlled by a TB, pinging and pre-detonation would occur.

Diesel engines have very large air:fuel ratios as high as 200:1 so there is no need to have a butterfly to control air intake...hence no throttle body to control in a diesel.

Whatever problem you may be describing may have to do with other aspects of the M57, but I don't believe it has anything to do with the "electronic throttle."