@suzook12 should be able to help here. Guessing you've already tried the obvious e.g. getting a spark at the plugs and clean filters etc?
How old are the fuel lines? If they're getting on a bit they can sometimes break down inside and block the flow of fuel with higher revs.
Right then, I'm gonna send them pics of my mighty, mighty dogfish catches wearing my OO hat, t shirt and hoodie, whilst standing next to an OO sticker! Bastards! 🤣
Sounds like a good plan. I've yet to explore much of the harbour but I've heard it can produce all the species in one way or another. Tight lines if you get out.