Dash cluster lights flick off, car dies

[LDundon]

Hey folks!
I need help!
My dash lights randomly turn off when driving and the car dies. Have swapped different batteries, doesn't change a thing. Car still cranks fine, will randomly start back up and go fine again for a few days then will sometimes flicker off then back on and the sometimes just off... car doesn't die immediately, engine is still moving... but as I come to a stop engine is off.
Radio lights etc are all still fine.
My guess is a faulty relay.... but which one?!

 

[naughtika]

have you checked the engine fuse at the engine bay? I think it's a 20amp fuse

 

[LDundon]

If it blows the car just turns off, I have 3 spare fuse boxes so no shortage of fuses or relays
Just want to know which one to check!