Pitch the foam filter, it needs to be a metal mesh that has 3 times the surface area and doesn’t absorb gas and moisture as bad blocking it up
You need to get rid of the thick head gasket 1.5 hp usually have, as well as inspect the top end, many times rings are or part stuck
Stock timing is not an answer, what is the btdc degrees? people who actually time their engine will say the degrees, People who did not time their engine just say stock and are missing one of the most important aspects of engine running