Idle surge, the almost die, then surge, then almost die

Hello everyone! Here is the latest bit of fun... Sometimes when I'm idling, my engine will surge, then almost die, then surge, then almost die, rather, rinse, repeat. The surge takes the rpm just above idle. The die takes it all the way to when the battery light comes on.

It's quite perplexing because it doesn't happen all the time. If I put my foot on the gas pedal and get the engine just above idle, it runs fine while stopped. Same thing when moving. No surging.

Soooo, what are your thoughts? Something in the idle fuel circuit, or something else?

Thanks as always.