When I put up the info (o) or details (ctrl+shift+o), display is good but as soon is I switch it off, it starts stuttering again.
Ssh to the device and try this command:
echo 750 > /sys/devices/pci0000:00/0000:00:02.0/drm/card0/gt_min_freq_mhz
If it works add it to storage/.config/autostart.sh