Iveco daily cold start problem?

hi, can anyone help. I have a iveco daily 2.8td 2002 model and has always started within a couple of rotations, until recently when the temperature dropped. I've replaced the battery and replaced the glow plug but the van won't start until you crank the engine over with 2-3 attempts. When started the van runs fine. Has anyone had similar symtoms and worked out what the problem was?
Cheers