Surging

I screwed up, and now my post disappeared, so I get to start over.
I think Mattax is right. But I also think TB is right. I think if you have a single cylinder there is no way for a lean misfire to back up into the plenum. But on a multi? I'm not so sure.
We have all probably seen a lean misfire back up into the intake when we whack open the carb and the A-pump isn't working right. I've had my eyebrows singed more than once, when I did this while starring down into the boosters.I tell you that's a wake up call,seeing a fireball coming up at you and you with nowhere to go.So, my question is; What lit that fire?
Idle-timing was probably 10 before,on the example I remember the most vividly, but I've seen it on 2bbl engines as well where idle timing is usually in the 0 to maybe as high as 8 range. So I'ma thinking on a per cylinder basis,under these circumstances, how could it be ignition timing? How did that fire get into the intake?
Or is this not what we're talking about?