Unstable idle, some vibs on 996
 

Please need your helps (excuse my American langage faults).

. 996 not drived during few years (old fuel) but engine started 1 or 2 times per year. I know it's not a good thing.
. O2 sensor not changed, this is only default appear on PIWI (I have to remove it).

I have an unstable idle and some vibs grow up when engine is hot.

Some vibs before I added new fuel (I had some of water condensation from 2 exhaust on short time):
https://www.youtube.com/watch?v=vjmJlleyFBU
https://www.youtube.com/watch?v=e6-9tBOTWLY

Around 85°C engine wants stop, if start to drive it, like muffled.
The idle is always very low when engine is hot (around 550-600rpm by 85°c. But idle is correct under 80°C around 750-850rpm and 900-1000rpm if 40°C).

Since I added NEW FUEL there are less vibs (around 30-35%) and no more water condensation in exhaust. But problem of idle and vibs are still present.

Do you hear something wrong in video (After new fuel) :
1- Cold Engine https://www.youtube.com/watch?v=eMoMk8mRxlM
2- Engine starts vibs around 50°C https://www.youtube.com/watch?v=sH-Q0giwjoE
3- Engine Hot: https://www.youtube.com/watch?v=AXnNkJIo2gQ

I have read the precious article about O2 sensor, and I am pretty sure I have to remove the old one. But do you hear something wrong as Variocam problem or Timing Chain ?

Many thanks - Yves

To complete first video, a new one with white smoke and water.
Engine just arrived at 80°c / 176°F. We can see smoke during idle and nothing during acceleration.
The fuel tank has been same during long years. I am trying to add some of Bardhal to dispear water inside the tank.
I believe that's fuel problem. And You ? Do you hear something wrong ?

https://www.youtube.com/watch?v=piLlArJ9_Nc

water in fuel will cause all types of weird random running issues. Just drive the car ..
once the lines gum up .. big bucks to replace them.
Italian tune up needed....