I have a few questions about my O.S. .40

I have been adjusting the mixutre and needle valv lately. After a few flights i noticed that fuel was begining to "cook" and turn brown on the engine. I was told once that this is normal and another time that this means it is running too hot.

I have plenty of residue along the side of the plane but there is also some brown residue in it. Is this ok? (I was told this is fine and is only un burnt oil cleaning the engine out)

Also, at the end of the day while flying and tweaking the engine all day, I noticed that the engine would bog down when I opened the throttle all the way. It died twice in air. I was told this is a simple needle valve adjustment.

Anyone mind telling me the adjustments I should make?