I have a 2006 2.0 diesel d4d it runs fine does not burn oil or blow smoke but it seems lazy to start when cold - use pre heat then turn key an count to 5 or 6 before it fires not sure if its related but every now and then it wants to tick over at 1100 rpm instead of its normal 8 / 900 rpm no amount of turning a/c or heater or any thing else seems to make a difference any ideas?