You could have a bad power valve, plugged air bleed, or dirt or fuel residue in the passeges.
I really doubt it's the power valve since the carb is so new.
The newer carbs are protected from blow out by a check valve.
Even the older carbs are not blown that easily.
Fuel can dry out in the bowl and leave deposits that can wash into the metering block.
I'd suggest removing the idle mixture screws and squirting carb cleaner in there. Then squirt carb cleaner on the air bleeds just inside the air horn. Do the primary and secondary air bleeds.
If it doesn't run better, check the float levels and if they are all right, you may have to remove the carb and blow it out.
Make shure the ignition is not the problem.
The black smoke is a tip off to carb richness, though.
Check my web page for First Gen Camaro suspension info:
David's Motorsports page
First Gen Suspension Page
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Can Am Vintage Racer
[This message has been edited by davidpozzi (edited 12-01-2000).]