First start with cleaning out both your FXO and Metashaders2 by deleting the contents, you will find this in DCS saved games.
Next clear out your DirectX shader cache (right click your OS drive and properties > tools> Disk clean-up.
You can also clean out the Nvidia cache located here C:\Users\YOURUSER\AppData\Local\NVIDIA (There's DX and GL cache folders)
With all shader locations deleted your game will take some time loading while it recompiles new shaders, load up the game and check to see if you are seeing any improvements.