Hello. Been using these forums for help with my old 2005 XC90 for a few years now, first time now where I've not been able to find a solution. This is my first time posting so it's possible i'm being a bit clumsy or posting in the wrong place.

Today while driving, near the right side bonnet/windscreen gap a very short steam cloud popped up along with a sound. I was going through a tunnel at the time and thought something fell on my car. But later noticed an unusual sound coming from the engine bay, along with general sluggyness driving. I recorded a video on it here Though in the video here I point to a specific thing, it could be anything in that vicinity doing that weird morse code sound going on.

The best I could find relating to what I thought the issue was would be this off-site post on the vacuum tank. But I'm not sure if that's faulty, or how exactly I would troubleshoot this. Unrelated but possibly related, for the past year have been having the check engine light pop on occasionally for 20 minutes or so, then goes away, very sporadic, and I've noticed when it does pop up the idle sound does change from the norm.

Any help would be appreciated, thanks!