honda eco hrg 41 mower?

Can anyone help please?
My mower starts and runs and then begins to misfire and backfire through the exhaust and then just dies. After a few pulls it fires up and the whole cycle happens again and again. As the engine warms then the ocurrence of the fault becomes less. I have had the top off and checked the air gap on the flywheel I have also checked the carb, fuel tank and spark plug. The condition is very similar to a timing and/or fuel fault.