Two years in and the issue didt go away, in very cold weather the jitters were hardcore. Replaced the battery two weeks ago and the problem has dissapeard. Started the car in 2 degree C and nothing. Im thinking the glowplugs didnt stay on long enough for the engone to warm up, but its strange that the car diagnostics wouldnt pick it up. When taken to inspection the faulty glow plug appeared again, so maybe the lack of power to gp showed up as faulty plugs?!