volkswagon passat 02 tdi se - airborne sean

can anybody help me !! i have had passat for just over a year, its been excellent however it recenttl started cutting out on me, after a change of fuel fliter everything seemed ok, howevr ive noticed now that before its warmed up sometimes it idles and stalls , then its a pain to start up! a bit of a drama when your at the lights, ive checked the glow plugs and had them cleaned but its only when starting ina morning, can anybody give me some advice on what it could be? my mates a mechanic [vw] but he is away , any help would be greatly appreciated , please contact me at xxiiipfa@hotmail.com
yours
volkswagon passat 02 tdi se - Alec
That'll be the coolant temperature sensor.
4-pin sensor on the rear of the head.