I think I am beginning to think this may be what's happening. I just went out and removed both pump arms and cams. I was wrong about the pump cams. They are both exactly the same pink cams with three holes. Same profiles and all. I don't know why I thought one only had two holes. Stupidity, I guess. Anyway, I did slightly adjust the primary pump arm a little flatter. Once I readjusted the pump sprAng, that seemed to solve it. But then, it started the stumble again. I looked and nothing was coming out of the primary pump squirter. Then it just arbitrarily started working again. So I think clearly this is an issue with the pump check valve. I'm tired of workin on it for today. I'll pull the carburetor back off maybe tomorrow and work the edges of the check valve with a file and see if there are any high spots. I bet there are.
