Carb flood, needle problems. Take off the carb, open and clean it, see the needle working and clean the seat, may be some dirt in the seat of the needle, control the float is good. I dont like plastics carbs!!. May be some black burn at the first (last flooded)
Focus the energy in the help to solve the problem. The only walking genius its Johnnie.
The engine runs in high speed, governor fails, change broken pieces you found and go.
My push mower,Honda clone (OHV) works with 20W50 oil, change every year in april, no problem never, lot of years
There is no oil that maintain properties more than a year after heated.
I think it's aluminium ( from Photo 1 and 6) try a magnet test, may be when you reassemble a little dirt stay inside and do the job. Wash and clean it all and reassemble. No ghost, only mysteries
The throttle in full power close the choke, and the carb is choke on. After the engine runs few seconds you must close the throttle at working RPMs, and the choke open to run.