Could be (if the engine is known to have good compression)

-Idle set too low
-One or more bad glowplugs
-Worn out starter or battery
-Rack Damper bolt screwed all the way in (tight) this caused mine to start poorly when cold, and also would occassionally stall when coasting...loosened rack damper...never happened again.
-Plugged fuel filters possibly?

Thats all I can think of....

__________________
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