1977 johnson stinger

[wartbd]

I have a 1977 75hp stinger short shaft with a jet foot, the engine starts and idles fine and runs good at wot, but will not accerate much past idle unless it is choked. The boat and motor are used primarily at 4000 to 6000 ft. elev. I have replaced the fuel line and primer bulb, the fuel pump has been replaced. Carberators have been cleaned and rebuilt and highspeed orifices replaced with proper size for elevation. All three coils have been replaced, power pack has been replaced. I checked the compression and with the tester I used compression was 130, 125, and 125psi. respectively. As I said the engine runs great other than the problem right off idle, any suggestions would be greatly appreciated.

[boats.net]

Sounds like a clogged air/fuel passage in the carburetor. Could also be timing.