[cheshired5]

It doesn't sound wishbone related to me so I'm more inclined to agree with the suspension theory.
On smaller P2 based cars, the shocks start to die around 140k miles so on a heavier XC90 dependant on how it's lived its life, similar could be happening at lower mileage.

You could begin with a visual test for oil misting on the shock and a bounce test on both front corners but deeper investigation would require dismantling of the strut assembly.