I have a 19' Tahiti hull with a Olds 455 and a Holley 750 Double pumper. It has a issue when you are cruzing at 2500 to 3000 rpm and you stab it, it starts to stumble and flatten out. I thought it was a fuel psi issue but it's a rock solid 9psi at any rpm. Thats what i thought it was so I am stumbed. so any ideas? carb jetting?