Golf GT TDi 1.9 (2000) - Starting problem - shaggy

Hi would appreciate some help my Golf 1.9 GT TDi 2000 has been taken a good few attempts to start hot or cold i have now change the glow plug relay(167) green coolant tempreature sensor and the glow plugs its now starting a bit better but not how it should be, still sometimes it may take 3-5 turns of the key,once its started i have no problems the car runs fine, before i had this problem the car sometimes would not start untill i had taken out the key put it back in again would that be the immobilizer and do think both problems are linked.