ok here is the problem at hand. 454 tunnel dual holleys .runs fine then when you get in the throttle is gose for about 5 five min or so and starts to loose power.let out of the throttle and cruise then get back in it same thing five min or less and starts slowind down . any suggestions. ive checked fuel pressure and volume. timming 

dual 650 holleys 3/8 fuel line 4200 rph holley manual fule pump with a electric fuel pump asist  ive checked at the carbs running a holley regulator  ive even uped the pressure to 8 lbs instead of the 6 i was running before .   

done that been fightin this problem since i swaped from a panther pump to this stupid berkley cause i coudnt get my rpms down now there down and it has this gremlin

Since the berk pulled your rpms down. It's putting a greater load on the engine.  Greater load means more fuel.   Your sucking the bowls dry.   When you get out of it fuel demand drops and the bowl level recovers.

it goes sound like you are running out of fuel do you have the clear sight glass on the side of the bowls to have someone check it out. ibhsbz i'm with you dry bowls

Run larger fuel line. Do you  have a fuel water seperator or a fuel filter? If so they could be clogged.

Chased a similar problem around on Pickle. IN the end, Rivertard was kinda right. He said he heard a distinct vacuum leak while in the boat at full throttle. Later, we tried timing, noone else heard the leak............Musta been the 'cow whisperer' in Mike that was the only one to hear it..........

In the end was a combination of problems. First, yeah, serious vacuum leak in the vac secondary bladder housing, as well as the bladder itself pretty much trash. (Explains why it would run balls out after idling a few minutes, but lift? ran like crap and would stall, spit and sputter, etc) That's one.

Second was the vacuum advance on the HEI. I hate HEI BTW on these boats, but it came with it, ran good for soooo long, but, after the carb problems were found, and fixed (By a fresh 850), had issues with the spitting and sputtering again at speed. DONE with the HEI. Put in a Unilte, which I know some hate and I love, been good in the driveway! we'll see what it does on the water! 

Ray

rev set at six and it would stay on the  rev would spin higher. went to an a/b stanless 63 mph at six .now 4200 and 55 mph.

I'm going with TJS on this one, sucking the fuel tank into a negative and impeding dinosaur pee flow...

GT