It vibrates when RPM decreases, a second later then it gets back to normal. (idles okay). Either cold/warm.
Vibration is not tough but want to make sure everything is okay.

history.
2007 s40. 100000 miles.
Had P0172 for 6 months and then problem fixed recently. (turned out to be clogged brake vacuum hose)
​​​After replacing it I erased the code with Bluetooth reader and no codes yet, no fuel trim issues.

 

The Electronic Throttle Control could be dirty. We have "drive by wire" and sometimes the ETC needs a bit of cleaning.

Have you changed the spark plugs yet? Could be a bit dirty if they are original.

 

Hello.
replaced at 40000 miles and then not yet.
​​​​​​​Actually I'd had a issue with P0172 for half of years so it might have faulted the plugs? (p0172 fixed now.)

 

Pull them out and have a look. It's easy enough to see if one has crud fouling it.