I need some help trying to get rid of code P0171 (system too lean on bank 1)

Same tune I had on the car for a lot of time, no new parts installed, had my turbo rebuilt by FP, and now sometimes (very often) when I spend some time on idle the wideband leans to 16/17 Short term fuel trim goes to max at 25 and code shows up.

Already tried to rescale the injectors, helped a little but stil shows sometimes adter idling for a few minutes without touching the gas pedal. Added some fuel on idle but no changes at all I guess because it is on closed loop. Tried disabling the code via periphery, did not work, since they are not labeled on the rom

Maybe try open loop full time? lower injector scaling another bit? clean / service injectors? do not want to change the scaling a lot, because I am tuned.

Any idea to stop getting this code?

Thanks