I hate when screens start to flicker.
Couple thing to check which might help.
Check your power, make sure you are not getting voltage drops, make sure you have a really good earth too.
Get some good video leads that have some good shielding, might also help
Where have you put the inline filters? how many have you put in? try hook them up as close as you can to the screens. Let me know if any of this helps and good luck.....