Hi all my galaxy seems to be a bit rough when I start it up cold now and again it seems to misfire it also does this when the accelerator is lighltly pressed i.e when tootling along at 30mph in 5th gear this sometimes causes it to judder badly until you put your foot flat down on the pedal or take it off completely then it settles down it seems to do it more when cold but has done the same with engine at norm temp had the vag on and no codes recorded, no air in clear pipe, fuel from the same petrol station as usual/normal colour smoke out back (i.e black) could it be either the injectors if so how can I test them or the glow plugs again how do I test them thanks any ideas would be very helpful thanks