1974 Johnson 25 hp electric outboard racing

[Relicboat]

I am new to the boating scene. I have a 1974 Johnson 25 hp electric start that when started it just races. I just replaced all the pump parts and everything else seems to be working. There is a black piece that is broken near the back right of motor and I can't identify it.

[boats.net]

Check the timing advance plate to see if moves freely from idle to wide open throttle, check throttle linkage and carb throttle linkage to see if binding and if carb throttle plates are closing at idle.