The controller is behind the right side headlight.
You could have a controller problem but the circuit to the trigger points are still what I would look at first. An easy test of this is to have key on engine off and move the throttle by hand. The pair of injectors signaled by their pair of trigger points closed at the moment, will fire twenty times from idle to full throttle (the number of times it fires is not important for this discussion). Move the engine by hand while continuously moving the throttle. The injcetors clicking will move down the firing order in pairs. When you get to the pair that don't fire check out the circuit.
Bosch Master, ASE Master, L1
33 years MB technician