sanger jet boat engine problems

[millwrightlong]

i could really use some help. i have a 18 foot Sanger with a 455 olds and Berkeley jet. the engine starts great, runs great, but. when under load the engine will only rev to 3900 rpms when cold and 3500 rpms when warm. I still have more pedal after hitting the current max rpm but when pushed beyond it runs but bogs down to about 32 to 33 hundred rpm. it will jump right back to 35 if i let off the pedal a bit. please give me some ideas.

i am new to forums so please excuse the newbie.

[millwrightlong]

compression is good, plugs look good, wires are good, hei ignition in good shape. carb is a Holley 650 with dual feed and vacuum secondaries. aluminum intake. engine was rebuilt and has 30 hours on since. mild cam with a real light lope and great idle. Berkley wet logs. please help