seeing as there is some interest i'll keep you updated.

i tested the battery, it started at 11.8V when cold then with the engine started it went up to 14.5V, apparently 11.8V is a bit low but overall the battery seems fine.

i have also found out that the idle control valve and automatic choke are for petrol engines and mines a diesel, so it's not that.

one thing i have noticed while checking the battery was that there is a hell of a lot of air going into the fuel injector pump from the fuel filter. the first garage noticed this and ruled it out but i didnt realise quite how much air there was, surely this air is being injected into the cylinders.

anyway, i have booked the car into Halfords, i'll let you know if they find anything.