This is the reply I got from Cobb:Cobb direct. Use their support email address. Be ready with your Cobb AP and with an installed Accessport manager on your desktop.
Sorry to hear about your experience with the stumble. You're correct in it being a fairly common issue. The throttle control tables used by Porsche are a bit lacking in the low input/low RPM scenarios. This leads to the ECU making some wider range interpolations for applied torque than would be ideal. We have somewhat smoothed it out with the OTS maps but it can't be completely erased. The custom tuning option from Flat6 might be a good option as they can more closely dial it in to your liking as opposed to our broader range OTS offerring!