Mines doing it too - but only when it's snowing. Even a light snow. It almost stalled on me this morning (cold start, not up to running temp, snowing) coming to a stop.
I've had the buck at just about any speed. And it either happens when cruising or in between hard (near WOT, let off to shift, back to near WOT) shifts.
I know I have a bad TC, and I'm beginning to wonder if that is the cause of this... Just haven't found enough time to pull the trans (my other car still needs a steering rack and windshield before its driveable).
you have an automatic, correct?
coils are the first thing you should be looking into... if you have more that 60k on them with this symptom presenting itself, one or more are probably bad and need to be replaced.