Technical Please help diagnose this stumble

I have a video but I'm having difficulty uploading it. The file extension isn't correct...

There's a weird stumble when I'm about halfway through the throttle; it sort of clears up if I feather the throttle for a second and then its good for the remainder of the acceleration.

This is a 241 Hemi with dual Rochester 2g's. Direct linkage. Petronix ignition. Car has been sitting for a while but starts, idles and runs fine.

Troubleshooting so far - rebuilt carbs / new fuel pump / new filter / fresh gas / new coil / thorough inspection of wiring. This car has ran perfectly well with this setup in the past. ( I did lighten the power valve springs in the carbs a while back to get rid of a previous stumble which worked )

Any ideas?

 

Do you know what kind of fuel pressure you have? Timing?

 

Fuel pressure is about 6psi. Timing is 10 degrees btdc.

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