"there has to be a reason for this"
Dude... ya got 60 psi of compression!
Its FFFFed up... there is no magic fix for it... you have to fix your piston/bore/rings to get it back up to snuff.
Till you do that... it isn't gonna run right... no matter what you do.
(the black down the side of the piston you mentioned before?... that was good detective work... it HAS to be fixed)
The cheapest possible fix... is.... get the cyl honed only... and get new rings...that would only cost $30 total (probably)... and MIGHT let it live another 500 to 1000 miles.