u/Boz1998

I have a family member that has an 2008 mini cooper r45 1.6 petrol that keeps cutting out, it started on Christmas day and I took a look at it, it was starting up fine but the moment I but it into gear or reved it it just cut out. It has been to several mechanics where it has had a new battery, new clutch and full service, it was working fine for a while but it cut out the other day and nobody knows why. I was thinking about trying to repair it myself but I have never encountered an issue like this and was wondering if anyone knows a potential cause to the issue