Is it the cable?
If you have an Edson pedistal with the throttle, it could be the bushing at the lever. My trans and throttle were very stiff and was told by the shipyard to disconnect the cable from the lever to determine if the cable was the problem or the bushing. When disconnected, if the cable is still stiff, that's the problem, if not then the lever will still be stiff and it would be the bushing. Try this unless you already know.