Well everyone, so the main problem of stutter on my time-lapse (being motorized or not), was mainly due to the fact that I was doing 24p sequences, even though the whole workflow was 24p from the very beginning in After Effects.
Since I do now my workflow in 30p ....no more stutter!!!
have a great weekend guys
Yes 24p is for cinema only. It's too slow for most of our time lapse work.