this reminds me of years ago on my 06 (only thing on it was Dezod S1 kit), and out of boosting in 4th, mashed in the clutch and the rpms dropped to 1000, then up to 1500rpms, then back down to 1000, then up to 1500 like 4 times. I put it back in gear and of course it quit. This only happened once. Dunno if that way maybe the same issue u had.

 

different issue but i have that too, both motors did it.

 

I'm having that same issue, the car also shuts down while in idle