Lagging Rochester 4bbl on 402 big block

[Chorner72]

Hey everyone,

This is my first post on here so forgive any errors. Recently hauled my 1972 Gmc Sierra Grande out of “ storage” after 15 years. After all the basics ( change engine oil, remove old fuel, blow out fuel lines, new battery, etc) it was wanting to quit on me once it reached operating temperature, seemed like it was flooding. So carb rebuild time. Stock 402 big block under the hood

Rebuilt the carb and it idles like a dream. One problem, upon acceleration it sounds like it just sucks air, almost to the point of killing the motor, then it will begin to fire normally if i ease off the gas.

Any ideas or thoughts would appreciated.

Thanks