Guys... I might have the solution as it worked on my D802 from Malaysia..
I've been facing the same jittering/flickering screen issue for the pass two weeks... I did send it for warranty but turns out to be my screen warranty has expired..
Even the technician said it might be the screen faulty.. But i did not trust him, since i have read few other guys in xda facing the same issue again after changed the screen or filter..
Atleast I saved few hundreds from my pocket..
1. Remove Weather Widget from your Home screen/Lock screen and force stop running Weather services in App Manager.
2. Install an App called "Greenify".
3. Add all pre-installed Apps by LG from your phone to be greenified.
Add into Greenify:
-World Clock Widget
4. Start hibernating those apps in Greenify.
After a while, my screen just stopped flickering.... Yeayyyy...!!!
Hopefully this solution will work with your phone as well... Finger crossed..
If you guys having problem going through these steps from your phone, try to cast the screen to your TV or use OSP on your PC...