Just to clear up the throttle issue, the E46 M52 motor uses an (MDK) electronic throttle (siemens MS42.0). Yes there is a cable, this is used to actuate the throttle potentiometers (just like the M54 which is part of the accelerator pedal - PWG).
The cable is also used has a back up in the event of the MDK failure however it does not allow full throttle. The MDK is controlled by the MS42.0 ECM/DME and is pulse width modulated in both directions (600Hz).
There are several more functions of this electronic throttle which is a course on it's own. When you look at the throttle you will see that one side is for cable, which again is for the potentiometer and fail safe operation. And the other side covered by a black housing, is for the throttle operation (MDK motor).