S60 cuts out at low revs
 

My Bi-fuel S60 2002 has started to cut out and stall - sometimes goes to petrol - at idling speed. I've noticed the idle revs sometimes drop to 700 and then it is likely to stop.
Any ideas?

Problem is most likely to be with your pressure regulator; either needs adjusting or rubber diaphragm has worn and needs replacing. If its factory fitted then it is probably a dealer only job.