Hi!
I never run a fuel line filter on the engine!! They can leak!
And never an airfilter!
Always filter your fuel with a small auto fuelfilter ( fuelfilters could be bought from an autoparts shop) put inside the fuel jug !
Never use a fuelfilter in-line at the carb on the engine!
What plug do you have ? Fuel?
Prop?

Regards!
Jan K
Sweden