Fuel starvation of 2007 Yamaha f115. Any advice?

I purchased a boat last year and has been running fine but recently i suspect the engine is being starved of fuel in certain scenarios. It started with massive drops in rpm while accelerating. It would accelerate for a few seconds before the rpm’s drop way down and slowly creep back up over a period of about 30 seconds. That issue has gotten worse seems to be happening every time I accelerate now. It has also started having trouble starting up. It takes a second to fire up. I have changed the fuel filter. No relief. No water in the fuel separator but loaded with rust/debris. I’m guessing this debris has gone further in the engine. What would you try next? VST filter? Pumps? Injectors? Any advice would be great