Hello, I have a 24 ft pontoon boat JC 824 with the 1986 Johnson outboard. I am having a problem with it appearing to get enough air. I have switched the oil pump out, adding a fuel pump and mix oil in gas 50:1 (i believe is correct). The motor starts however doesn't idle well and bogs out when giving gas. If you take the cover off the engine it runs fine. My brother put holes in the cover and then fine screening and that helped some but not great. I need ideas please. Also, I know this is not the original prop for this boat so if anyone has ideas about size and slope of prop that would be great. I cannot read the one that is one there however it is 3 blade prop. I appreciate your time. Thanks