And how did you put the oil in? through the glow plug hole? None is getting in the Carb is it?
I believe 3in1 oil is a petrolium based oil much like it's brother WD40,
Not good for the silicon O-rings and seals of a glow fuel motor
Just a thought,,,,Makes me wonder

I had a leaky fuel filter once,,,look there too
Have you dismantled the carb to look for debri blocking jets?

If the front bearing was leaking you'd have a lean condition through out the rpm range,,,not just at idle,, and you'd have raw fuel/oil as evidence. I've had leaky bearings and the engine idled fine,,,just made a big mess and ran hot

Hope you find the solution