300tdi auto (EDC) revs hunting and surging - idling+ driving

Hi all,
My friends 300tdi discovery auto has recently become very erratic when idling and the revs hunt up and down when driving making it difficult to maintain a steady speed, it occurred soon after I replaced the starter motor for him (not sure if just a coincidence), but wondering if the rectifier has gone in the alternator causing fluctuating voltage effecting the governor on the EDC pump?

Will test the diode continuity soon but has anyone had a similar issue caused by an alternator fault? My auto is a mechanical pump so I'm not really familiar with his EDC system.

Thanks

I would ignore the fact it is an EDC to start with and check the fuel supply to the injector pump

lynall said:

I would ignore the fact it is an EDC to start with and check the fuel supply to the injector pump

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Ok thanks, was just thinking it's likely electrical since the old starter motor coil was seizing up and overheating from the current, possible effecting the alternator? Also the engine light has starter flickering on and off.