Attaching Youtube video that indicates the problem the car has been having as long as I have had it.
The car has random RPM fluctuations only when the engine has reached Normal temperature and it happens in all driving modes, D, N, R and Park and through different gears and Idle. Usually last for about 1-1,5 minutes and then several minutes before occuring next time.
Since video can be shown here in the post I will copy in the description below with the times of the fluctuations.

The video is at 2x speed in between fluctuating periods. The Video is recorded during 1 drive from engine cold temperature for a duration of 50 minutes where about 10 of the minutes was fluctuating periods.
For the remaining 40 minutes between fluctuating periods the speed is increased to 2x or about 20 minutes.
Fluctuating periods are as follows:
From 7 minutes to 8 minutes: Fluctuating RPM at both D and P
From 10 minutes to 11:30 minutes: Fluctuating RPM in R, N and P
From 18 minutes to 19:30 minutes: Fluctuating RPM in D at different gears
From 21:30 minutes to 23 minutes: Fluctuating RPM in D at different gears
From 26 minutes to 27:30 minutes: Fluctuating RPM in D and N

 

Please read the DTC codes and then share with us.

 

Year, mileage, has anything been worked on lately? Have the MAF, O2 sensors, DISA valve etc. (how many miles ago?) been changed out?

 

The car has approx 120000miles and it has been like this since I bought it 8 years ago, but then again I have only driven like 10000miles on those 8 years so it has not bothered me too much. And I have checked the Inpa for errors but nothing has ever come up in regards to engine sensors or other components of the engine.

 

That's weird, usually those fluctuations come with a couple of errors regarding mixture, misfires or whatnot. What's the model/code of the engine? Also, I'd check INPA for adaptations, could be overcompensating for a small enough vacuum leak that manifests itself fully when the car is at operating temperature. If you have access to it, make a smoke test, see if you find any vacuum leaks.

Some other things that could shed some light: how many kms do the coils have? Sometimes they fail intermittently, and with no warning or codes present. Are the sparkplugs clean or have some soot?

Other things could be MAF, malfuntioning throttle body, clogged or malfunctioning injectors, etc. If there's no errors, I'd do some more digging before starting to shell out money, those issues can be a money pit sometimes, specially when you start replacing things like injectors, coils, MAF, etc.