Typhoon 50 2stroke cutting out after a few miles

Hello all
Recently got a 50 back on the road , standard apart from derestrict exhaust and inlet manifold , 66 main jet , starts great , runs great for a bit then dies , leave for a few mins and we are off again , ordered new plug as I don't know how old it is , any ideas ? Carb is clean new hoses , new vac petrol tap , new electronic coke, fresh petrol , could the coil be breaking down ?
Many thanks in advance