Thank you so much for all your help !

What I did since my last message was changing oxygen sensor, but did not help to resolve my problem, but was good thing to do anyway 😎

Then I tooked the injectors out to test ( resitance and spray pattern) and found out that one was off, only functionning badly. I cleaned them all out and sprayd carbcleaner through it till they sprayed nicely and fine. Put a new injector repair kit on it with new o- rings and put them all back with new silicon grease - but the engine fault code came on again anyway. So I surely did some good to my beloved Volvo, but did still not resolve my problem.

This after-noon I changes my coolant temp sensor under cylinder No 3 ( the sensor which is talking to the engine control unit, very important for fuel trim) and hello ! Good morning ! Here we are ! Life is beautiful ! Volvos are great (again). 😀😀😀😁😁😁😁🎶🎵👍👍👍🌞🌞🌞😀😀😁😁😃😃😆😆🤣🤣😅😅😅 the fault code went off - I found the problem, pretty confident, will testdrve more tomorrow.
This issue tooked me 6 months at least to resolve !

Thank you again all - much appreciated !