Hi guys, just after some advice on a problem with my 2008 Mazda 6, 2.5L Petrol. 155,000kms

A month or so ago the engine light came on, but no real problems showed, apart from a stronger than normal petrol smell in the morning.
Recently I had the car serviced, and the mechanic plugged in his tool and it showed an oxygen sensor fault. Still the car was running fine.

A few days ago the car started to idle really low and turn off whenever I stopped. I disconnected/reconnected the battery and this seemed to help.

I did a few searches and found I might need to clean the MAF / IAF? Could this be the issue, or something different?

Thanks!