Starting with the basics is essential.
However, fuel dripping into the carburetor was mentioned. When the engine is cold, the engine is not complaining, but is running poorly when hot. When the engine is cold, it requires a richer mixture, so the drip may be satisfying the engine's fuel mixture needs. I theorize that when hot, the drip is causing the mixture to be too rich. The carburetor may need a float adjustment or possibly further tear down/clean/reassembly. I suggest to start with the basics, but include the float adjustment.