General, use heavy duty caustic carb cleaner in the ultrasound bath, do it in a very well ventilated area...the fumes will kill ya. Sounds like you have a blocked idle air port or idle fuel slot feed passage.
Sir speedy your carbs are what kind again? your description doesn't make sense to me,"Edelbrock/Weber AFB-style 600cfm carb." Are these Carter two barrel carbs...six pack setup? What cfm per carb? <img src="confused.gif" border="0">
Outlawed tunes from outlawed pipes