This is fixed. In the SCT software under dashpot settings there is a setting called "dashpot settling time". I have always set it to 0. My original tune may have had it set that way. I accidentally reset the dashpot settings to default in one of the tunes and noticed that the return to idle was much better. That got me going in the right direction. Idles at 650 rpm and return to idle with no stalling when returning to idle. Video attached.