Breaking up in third gear

[Wayne7]

I was running the TA testing for an upcoming road course event .
It would run through 1-2 then in third and forth it would breakup
And loose power surging like it was running our of gas.
I have a 1/2 pick up from robbmac feeding a Holley
Blue to 1/2 lines to a Holley dead head pump into a Holley
950 hp carb. This is a old combo nothing new that has worked well in the past at the drag strip.
Dome things that struck me as possible issues the engine was running hotter that it has in the past showing 220 . Also runs with the temp below 200 seemed clean. Is it vapor lock or the pump ???

Thanks
Oh engine is a Pontiac 455 about 550 hp fwiw.

[Shaker455]

Start with looking over your cap & rotor.

You should have a 10 micron filter right before the carb

Break the carb down and clean,post all specs jets, PV size etc.

[705.0Merc]

Could also watch a fuel pressure gauge while going for a run to see if it stays steady.

[Blown73]

Start with getting rid of the holley blue.