Hello-
I have had similar issues with a 98 V90.
So to clean the breather and associated hoses, you need to disconnect the fittings at the air intake. There may be some type of hose clamps that are difficult to remove, as they require a special type tool. I used pliers and a small pry to get them off- the breather itself is on a swivel fitting. There is a "o" ring that seals the coupler to the hose, be careful not to damage it when removing. I cleaned the hoses and the breather, which made a big difference in the performance of the engine. I don't think maintenance had been done on this area since the car was new(er).

The plastic strainer (breather) can be bought from FCPEuro, along with the entire needed gaskets and hose fittings if you want to do the complete job. There is a DIY video on You Tube describing the replacement procedure too.
I didn't do the entire repair, but plan on it later in the spring, when the weather warms up. For now tho, the small cleaning I did helped. Good luck.
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89-740 GLE;91-940 Sedan ;98-V90 Wagon ___ all running well