Thanks a lot for suggestion, but deffinately not (they would have to be warped quite a bit i guess) and there is nothing when depressing the clutch and the car is just idling but still up to speed..

the pulling feelling is kind of the same rytm all the time, in different gears (lower gears)
you could also say it feels like lifting throtle a little bit, and pressing it again, and keep doing it in 1 second rytms.

i seems to me that it must be electrically, as the "rytm" is constant
but I could be wrong