Well to start i think it may be the air mass sensor. I got a Peugeot 2.0 ltr HDI 2006 model, recently it had some trouble with power. Like it lost boost when it wanted to, but before that i had troubles starting. It would take around 6-8 tries at staring at times (random times no pattern).
Just after i noticed the hard starting i took it for a service which was 2000km before it was due, it's when i left the mechanics that i noticed the loss of power. It was around 30% loss to begin with so i took it the long way home and it seemed to loose ALL boost. What normally went from 0-60 in 11 seconds was now taking 21.5 seconds, booooo!! Anyway it seems to have cleared up the power loss/turbo lag problem but now the hard starts are becoming more common, i know it will start however it is beginning to be a major PITA. The starter motor must hate it!]
I have also thought about a stuck wastegate (these turbos use an internal wastegate) but that does not explain the hard starts.