I have a V40 with 122,000 miles. About 4 to 5 years ago it started to sporadically drop subtly the RPM. It does this no matter the weather, air on or off, etc. the dealer about 2 years ago changed the idle sensor. The problem still exists today. This does not affect the performance of the car. I bought the car new, the transmission was replaced about a year and a half after I bought the car.
If it’s not shaking the car, at this age and mileage, I’d forget about it. (I would, however, mention it the next time it goes in for regular maintenance.)
Have you had the ECU scanned for fault codes?
No,I have not. Can ask when it goes in.