Quote:

Almost any vacuum leak will cause a problem.
...


right, while I'm checking in mid-stream, just wondering if sorting the carbs is chasing a symptom rather than the cause.
I noticed op's other post of the sooted-up/white insulator plugs.
Got me to thinking that a vacuum leak down-stream of the carbs may need investigated. i.e. a split booster diaphragm that opens up under high vacuum only.