Did the EGR and pipes get de-carboned?
If swirl arm is broken it’s because the flaps are crusted with soot.
Needs new swirl flaps, clean the valve cover and piping with a carbon cleaning machine, maybe new actuator, the arm comes with flap kit.
Expect lifters and arms needing done too.
Injectors fail as well.
See the other post on here about xc90d5 I updated costs on that.
You need a workshop for all of above.
