Victa Vantage 201K - Fuel flow problem? Motor keeps dying?

I have a Victa Vantage 201K 2 stroke lawnmower - near new. It starts first pull, runs for a short whilke and then starts to die, revs up again - then starts to dies, revs up again - then starts to die, etc etc. After about 2 minutes running like this, it stops altogether. A few minutes later, I can start it again with the same cycle all over again. I have cleaned the carby, the fuel filter screw (at the side). All seems OK. I have visually checked the diaphram in the carby and it seems OK. Can anyone please offer any advice on what could be wrong and how to fix it. Cheers Jon.