Factory 4bbl manifold. It appears to be popping only, haven't seen any flamage, it does it when accelerating from no/low speed. If I'm at a cruising or highway speed I can romp on it and everything's fine.
Drove it about 40+ miles today, at one stop about halfway through it popped so bad it blew the vacuum cap off of the PCV fitting on the carb, (I'm using the stock carb spacer fitting for my pcv.), and it was a new cap that was pressed on pretty hard! With such a huge vacuum leak the truck wouldn't idle and my brake booster wasn't very effective. I stopped at a parts store and picked up some new caps and I'm back to where I started now.
Sure sounds like it has to be the carb to me, don't know where else to go at this point.
Except for the almost dying part 
. Does sound like it was the Holley Hiccups since it appears to have been running lean on the primaries. Good job. You may want to consider getting a set of non-stick gaskets for the fuel bowl/metering block. They will allow you to repeatedly disassemble the carb (well, within reason) for jet replacement until you get it dialed in. Also, if you buy different jets, make sure to get Holley jets. Some aftermarket jets, like Maxjets, available from Jegs, do not directly correspond with the Holley sizes.
What makes it suck more is that the cable was only a few months old. Another $20 blown away. 
