Echo blower dies when hot

PB403T backpack blower runs fine for up to 45 min and then surges for several min and dies. Swapped carb. New intake gaskets. Swapped coil. Removed gas cap. New plug. New head gasket to replace the old one that was leaking. The cyl and piston are scarred on the intake side but the compression is 70psi both when it's cold and hot/dead.

Any ideas?

Thanks,
-Roland