You may have surmised this, but it sounds like an ignition/and or electrical problem. Do you have the computerized MSD ignition? Maybe it was fried or defective ? Maybe there is a crossed wire in the build? (I am assuming for the moment that this is a new build)
The problem mat have been compounded by the first carb ? But maybe you have half/fried a wire/the computer, in the meantime, so it came back?
If it was mechanical, the problem would have been constant ?
Just guesses, maybe someone else recognizes the exact problemo and can help
By the way, I never rebuild carbs, I buy quality rebuilt carbs and just drop the puppy on the motor. Did I mention I HATE carbs? My dad can rebuild them in his sleep, I HATE them
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