hesitation when cold

[mcbutler]

Hello all, I have the 2.2 puma engine in my jumbo.
The van has 100K miles, full service history and has always run faultlessly.
Every tank of fuel has injector cleaner added as well.
This morning on cold start it was a bit rough, this caught my attention but at the end of the day its a diesel!!!!
Anyway, off I went down the hill, under the bridge - red light - then off up the gentle hill. Around 2250 rpm i felt a light hesitation. Not the savage bang you get with fuel loss etc. I backed off the htrottle and all was well, more throttle and it reoccured...
A mile later and van only slightly warm, I parked for two hours. On my return trip on an even steeper hill all was fine.
So, any ideas van gurus?????????