Car stuttering when warm but not whe cold

could be electrical, have a good look at all sensor connections etc, and see if you disturbed any when fitting glow plugs.

I thought of that dog68, and have checked all connections, funny thing is the car was running fine for a couple of days after i changed the plugs, then one day of all sudden it happened, as ive said it is fine when cold as soon as it heats up it starts, i disconnected the sensor at the air filter, what is it called again the air flow sensor or something but still the same, need to spend the day looking at everything and trial and error unless anyone else had the same problem

Eventually found and rectified the problem, when putting in my glow plugs and tightening the 8mm nut which holds the connecting length of wire i must have overtightened one of them as it had snapped the core of the glow plug, either that or a defective glow plug, id say a defective glow plug as i didnt tighten them any more than hand tight, the nut was making the centre of the plug turn so in effect not a great connection, bit of a weird problem the way it was affecting the car, only when the engine had heated up, anyone shed any light on why that would happen, i rectified it by buying a new glow plug (ngk) dont think i need to replace all 4