This thing is sporadic and hadd to replicate. When it happens the check engine light comes on, if i restart the engine , the light goes out and it stops dling it for the duration of the drive. The are no codes when the light comes on.
Here's what it does. Stopped engine running in drive. The car feels like it shifts into 2nd while sitting still. The next thing it will do is slow roll like a manual without the clutch engaged until it gets up to speed and shifts normally. When it is not...

2013 GT Automatic Shift Problem