Starts ok.
1st gear, progressive acceleration, ok.
I stop pushing the throttle, let's say at 2500rpm or 3000rpm, ok.
No brakes applied.
The rpm start dropping slowly as it should be, but near the 1500rpm both car and engine shakes/hesitates like wanting to go forward-backward.
It continues for few seconds until the speed/engine/car is harmonised to 800-900rpm.
If I want to stop this issue, I have to apply half clutch to eliminate shakes/vibrations/hesitations and make a smooth transition from 1500rpm to idle rpm.
It happens the same with 2nd gear but with higher gears 3rd and especially 4th, 5th, it shakes much less.
Just stop pushing the throttle and there is a minor shake, the transition is not smooth, and in lower gears 1st and 2nd it is much more sensible.
It looks like the problem is from 1500rpm to idle in lower gears while in higher gears the engine shakes less to find its equilibrium.
I've changed just once the clutch (160k) but not the flywheel. My Civic has 300k but this issue is present since 90k and with time it has been slightly deteriorated.
Maybe is not the flywheel but a sensor, map, iacv...

 

The flywheel ( pressure plate I believe ) should be machined when the clutch is replaced or you can get chatter , At any rate I think that 's where the problem lies with the clutch assembly