D4D 2006 - "hesitation" when gas pedal released

[Geir G]

Hi, I have the 116 hp D4D.  I have been having a strange issue which only happens when I release the gas pedal while the car is in gear.  So when I am driving and I release the gas pedal with the car in gear, the rpm starts to go down as it should but then it starts "hesitate" just for a split second.  What I mean by that is that the rpm stops going down for just a short part of a second, then maybe 1-2 seconds pass and it does it again and again.  

I remember a few years ago I had a different type of car with a faulty throttle position sensor.  To a some (very small) extent this reminds me of that but then again not, because the rpm isn't going up in my current situation.  When the rpm is dropping then just suddenly for a split second it  stays the same so I experience it as a sort of a hesitation which is very annoying while driving.

I tried to catch a video of it, but it is difficult to see but at least at around 1800 and 1500 rpm it is noticealbe.

Has anybody dealt with this?

I have no error codes.