Could this be a fuel delivery? Video

[iwaterdave]

I just put new gaskets and cleaned all fuel delivery ports. No air leaks in fuel lines, and confirmed spark in both cylinders. I'm at a loss to what to look at next. I'm sure I put the gaskets in right. (outside in: diaphragm/gasket, diaphragm, gasket) This is a 75 Mercury 7.5hp Serial number #5018561

 

[jimmbo]

Sounds like it running lean. Have your tried adjusting the idle mixture?

 

[Chinewalker]

I agree, sounds like a lean sneeze. Idle screw might need to be opened up a bit. It's the slotted screw at about the 2-o'clock position on the face of the carb.