Is there anyone else with the GD CVT that can shed some light on my issue?
I had a simlar stiuation recently, my car dropped below 500rpm and sometimes stalled (I have the cvt-7)
everytime I stopped at a robot I had to push a bit down on the throttle to keep the rev's just under 1000rpm while holding brakes in, I also noticed that my brakes felt like it was not working properly when I braked whilst the revs jumped below 500rpm but worked fine at a higher rpm.
A few days later my D light started to ficker and car went into limp mode.
Just last week friday I took the car to mayfair gearbox auto devision here in Johannesburg.
they tested the gearbox only to find out that the box needs to be rebuilt.
I don't know if that is what happening to your car. but for me it was my gearbox that was the issue.
I will attach what Mayfai has found on my car.