Fuel Pump Issues??

[StrokerCobra]

Guys recently fitted a Holley Blue (with dead head style reg set at 6.5psi) because I've had a bad run with the hi-volume Holley mechanical pumps falling to pieces.

Thinking I have a fuel delivery issue with the new set-up, hopefully someone can help.

Flat out through the gears I'm finding in top gear I get a surge coming in 5000+ only in top gear on a warm day. Not on a cool night, and not in any gear other than top.

Never experienced anything remotely like it, guessing it could be the fuel pump running out of puff, but don't know why it makes the motor surge. When I've had mechanical fuel pumps before that weren't up to the grade motor just went bllaa and died off until it picked up again.

Anyone experienced something like it?

Getting ready for the street drags next Wednesday and want to get it running spot on. Will upgrade to a bigger electric pump if it turns out it is the fuel pump causing the surge. Got any suggestions? Ideally a return line and BG pump would be nice, but don't really want to re-fabricate the whole set-up at this stage...

[StrokerCobra]

As an addendum..

Been suggested lean secondaries can give rise to the surging.. Though I'm pretty sure at WOT primaries and secondaries combined, the mixture is spot on as far as plug readings go.

Any opinions?