Well, I don't know what exactly to tell you but my wife's car no longer does it.
I was under the hood a few weeks ago - changed the oil, wiggled the wires going into the MAF, looked around for any wires or hoses loose (didnt find anything) Started the car and let it idle, then revved it trying to recreate the problem in the driveway to begin unplugging fuel injectors to locate a bad one but it never came up.
Since then it hasn't come back.
I'm happy but puzzled.