Yamaha F150xa rpm loss

[Surfjones3]

Hi all,
having an issue with a 2014 Yamaha f150. The engine has about 600hrs ram great all season. Currently everything is good idle is right where it should be. Accelerates good. When I get up on plane I’ll run between 4000-4500 rpms after about 5mins of run time I get a big power loss, the rpms drop from the 4500 range and fluctuate between 2500-3500 the engine never stalls though . I initially thought this might be a fuel problem and my lift pump was bad but I have literally ruled out every part of the fuel system from the tank to the injectors and it still does the same thing. Anyone have any ideas ?

[99yam40]

how did you rule out all of the fuel system?

did you monitor the rail pressure to see if it stays in spec while the problem shows up?

[Surfjones3]

Injectors cleaned, VSt serviced (ethanol gas broke Down a fuel line, it got sucked through the hp fuel pump and seized the pump, all new high pressure fuel pump, high pressure lines replaced with new ones) new fuel water separator new inline engine filter, new primer bulb and fill lines from tank to engine. When problem occurs the bulb is not getting sucked in, ran engine off separate fuel tank and same thing happens, the primer bulb can be pumped to solid when the rpms drop and it doesn’t change anything, looked at the back and inside of the lift pumps and they look fine. Also blew the vent out to make sure it wasn’t clogged