[DaveC]

Lift your boot cover and check that the boot is not full of water.

 

[DaveC]

This may not be of any help but i had something similar on one of my vans and on a mates car.
Basically the sill drains were blocked, again this may not be relevant to Volvos but if you feel along the bottom length of the sills you might just find bulges which have holes (possibly 3or4 each side) that are blocked and need poking out with the end of a 'plastic' tie wrap.
The amount of water that came out was unbelievable but it cured the sloshing sounds.
Good luck.

 

[DaveC]

Can you be more specific of when you hear the sloshing, is it going around corners or when braking and accelerating.

 

[DaveC]

I hear it mainly when i brake and i come to a complete stop. Right there and then i hear it going Glorp-glorp couple o times.

I'd put money on the sill drains being blocked then.
Feel long the sills and you should feel bulges where it seems as though the sill and floor have not been pinched together, these bulges should have holes to drain the sills, prod them with plastic not metal as metal could remove protective paint and cause corrosion.
You could also find these holes have been crushed/closed by someone jacking the car up in the wrong place.

 

[DaveC]

Did this problem get resolved?????