What the surge at idle??

What's the deal with some of these cars with mechanical injection and blower that surge at idle. No matter if in gear or neutral, these car surge big time. The whole car rocks side to side. The engine about dies, then surges back up.

It makes a sound like: woorh........woorh.........woorh.....etc.

I seen a corvettle at the track last test and tune and it was cool just watching him in the staging lanes trying to get to the lights. The car only moves forward when the RPM spikes up. Anybody know what causes that??

Maybe like waanh..........waanh..........waanh........sound like my wife trying to explain the noise her car makes...