Peugeot 306 HDI: Misfire & Hesitation (05/2000)

I WOULD LIKE SOME TIPS
REGARDING ROUGH IDLING AND MISSED IGNITION SPARK PLUGS WHEN THE ENGINE IS COLD.
It is reasonable to assume that a single injector is more likely to fail.
ACCORDING TO THE WORKSHOP, EVERYTHING IS FINE.
AT BOSCH, THEY WANTED TO REPLACE THE STEERING UNIT IMMEDIATELY.
THE VEHICLE HAS A RHY DIESEL ENGINE WITH A BOSCH EDC 15C2 ENGINE CONTROL UNIT.
IF ANYONE HAS HAD OR KNOWS ABOUT SIMILAR PROBLEMS, PLEASE FEEL FREE TO RESPOND.