Thanks for the reply. We just checked the cables and linkage and they are fine. It is all attached and has the right "travel." The engine has run properly for the last 1.5 years we've had the boat and 200ish hours of use. The only thing we have done to the engine recently is change all the fluids and oil filter, which it worked just fine after. Then I went to change the Racor primary and the on-engine secondary filter, and once I got the new filter base and filter installed and re-primed this happened. So...I believe it to not be a random problem since it was working fine right before this.
If possible, it might be worth a try to re-install everything back to before the high rev issue and see what happens, or to temporarily by-pass the filter in question?