2005 Mazda 6 petrol cutting out fault?
 

I've got a 2005 Mazda 6 petrol low miles ive just changed oil and filter plugs and air filter to try and find problem as car runs perfect until you come to a junction then cuts out, it will restart straight away but cannot gins this fault ? I've has diagnostics done and no faults coming up and no lights on dash, yet it's still cutting out any ideas? I've looked for obvious faults holes in pipes etc but can't find anything really hope someone can help on this..