Street Racing A Nova !

I'm back for some desperate help. You guys are 100% so far.
I have a 1968 Dart with newish 360/400hp engine.
So a new development , I was doing a little street racing in the valley over thanksgiving with a (70's nova) and had a strange engine problem. Take off was great, nice traction floored in drive got to 5,200 rpm screaming in first gear , then trans shifted into second and engine totally started missing. like it was running out of gas, white smoke I could hear the carb sucking air and no power floored it would bounce to 3,500 rpm and stall back down,ping, rough you name it. I let off the gas and tried again and it recovered some what and I finished, but it never really kicked in. So lost the race big time and I want a rematch. Afterword the car ran fine , I got on it again no problem. Then yesterday I was getting on it from a stop light and it pinged and lugged and stalled again. Now it fine. What do you think carb, vacume , ignition ? Its running a little rough.
Any advice ?

Dale