Sounds like a new engine. Break in with liberal amounts of Castor oil in the fuel. Use the heat gun to warm it up, then fire it up. After the first run it will be looser.

Old heads say use fuel with 20% Lube in it. If you have the "Standard" blend with 17-18% lube, add a couple of ounces of Castor oil to it. After the first gallon is through it, use what you want, all synthetic or a blend of standard mixed fuel. I would always have some Castor in the blend, but that's me.

Cheers,

Chip