Ok sounds like you have still got a carb ration issue . Or a crank seal gone on the left side of the engine causing oiling up of the plug . I went out on my beta last week and Wass on it for 5 hours and it rode perfectly constantly all day . With it not responding when u try to wheeli sounds like it's bogging out and has no power antill it clears out the unburnt oil . Does it idle , or you could find the float hight is too high flooding the engine on the steep hill decent . Trick one to diagnose with out being there