gargle when I lift?

[Perfectlap]

Name this sound if you can. First its a gargle and not the typical rumble of an aftermarket exhaust. The gargle occurs when I'm cruising along in first gear usually. I step on the gas from a stop, for instance when exiting the parking garage where everything echoes, when I approach a stop sign and get off the gas, after a short pause I hear the gargle. Seems to be tied to the throttle action if you will. Coil packs?