I have a 2018 Outland and it was stood for a week while I was away, then driven and straight away didn’t feel right It was as if I was tapping the breaks I got home put a code reader on and it read p0107 which is a air flow sensor so i replaced it but it is still juddering and loosing power and now black smoke pretty much continuously whilst driving ? Its worse in lower gears
a friend suggested using red x diesel engine cleaner which we did and it has made a difference

Car is booked in for a full service Thursday earliest I could get it in but we are worried that driving is causing more damage
anyone got any ideas what it could be ? And is driving damaging it ?