Actually video link looks like working for me but strange. I will upload video from other website. Closer to end of video at it's more noticeable as I decreased idle speed to 400rpm.

https://streamable.com/j2mgu

I will try to describe the problem. The 'surge' I know. If the piston of aux air slide valve got stucked 'remain open' too much air entering to engine and rpm increases till 1500 or 2000 rpm even then ECU cuts off fuel like you expained to decreases replt to 750 or Idle speed and this loops continues till warm up or sometimes forever if the aux slide valve borken or defective.

But my case, when I listen exhaust sound, engine runing normal but there is a'pıt' 'pıt''pıt''pıt''pıt''pıt' sound intervals during idle operation or cold start. It looks like some injectors are not working or imporperly spraying or not inorder with timing if so how can it be?

Sorry I can describe sound like this, normal exhasut engine sound ''mmmmmmm then pıtpıtpıtpıtmmmmpıtpıtmmmmmmpıtpıtpıt''unstablility or interruption like wrong timing but I have ignition gun, checked timing is stable no deviation..

As a notification, at cold start, engine does not run high speed, normally it should work around 1200rpm at least as the weather aprrox 18 degrees now. But my case engine runs around 900 rpm at cold.

I don't think so that this problem because of ignition, because when acceleration no interruption(misfire). Everything is normal, but I'm sure this tiny idle speed misfiring is somehow related with fuel suppy.

For this case I also checked fuel pressure , it's stable at 2bar at idle or when push acceleration but this problem still available .

Checked trigger points cleaned nothing changed, tried spare ecu same, tried with new MAP which I keep as spare same, checked with other distributor same.. Just did not try with other set of injectors as I don't have 8 spare.