[binty]

Had similar symptoms on a Renault it was water in the body control unit.
XC 90,s before 2006 have a known weak water seal on the CEM.
First check for me would be to see if it wet under the drivers carpet as this is where it can gather. The cem is directly above the accelerator pedal.
unclip the centre console carpet trim and work your hand own near the handbrake pedal. The carpet and foam is about 10 cm thick so make sure you get to the metal floor.
If it’s wet there are loads of posts about it.