Edelbrock setup for dual quad

Ok, still needing advice. Altho it fires up great and drives pretty good, there are still issues.
After approx 10-15 minutes of driving, there will be a "surging" that is fairly rhythmic. Once I change speed by either decelerating or accelerating, it goes away. It does come back tho. Only when in a constant speed.
Heres current pics of plugs I just pulled. Autolite 66. Black/rich as fack. Plugs appear to get progressively worse from front to back.
Going to put Champion N10Y in tomorrow.

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