Yes it is a 2 stroke.----Mix at 50:1 in the tank.----Install a new water pump impeller.----Find an owners manual.----Read it 2 times before your first fishing trip.
There are lots of exhaust bubbles in your bucket.-----Fooling you into thinking it has lots of power.----Agreed sounds like it is running on one cylinder or throttle cam might be broken..
Do you change light bulbs in the kitchen before they pop ?-----The electrical bits are quite well made.-----New impeller every 4 / 5 years is all I would do.
They did not leave the factory with a tell tale as is found on a 1979 3 cylinder motor like yours.----Test your overheat warning light!!-----Install a new impeller now and every 5 years.
I believe you are overthinking on the timing marks.-----A wise man would install a new impeller.-----These motors do not have an overheat buzzer.----hey do not have a shutdown on overheat feature.-----It will run until it is far too late !!
It did not come with a tell tale like newer motors !!!!------You must install a new impeller too.------Or test the overheat warning light.----Better yet is to install an overheat buzzer!
You must realize that nobody can see , feel your motor up close.-----There might be something simple that is wrong.-----I believe you are struggling because you mis-understand some of the excellent advice posted here.