Vizio picture cuts out but still has sound

I have a 65" Vizio TV (D65u-D2) and the picture cuts out after a couple of minutes but I still have sound. When I first turn it on the picture is fine but after a couple of minutes it will go black but still have sound. The odd thing is if I hold the mute button for 3 seconds and then press OK the picture will come back up but will go back off after a few minutes.

This is what I have done to try and fix it:

-Turned auto brightness off (didn't see any other backlight settings other than that)

-Unplugged the TV for 5 minutes and plugged it back in.

-Unplugged and held the power button down on the TV for 30 seconds and plugged back in.

-Checked to see if it was the cable box by turning on Netflix, still did it.

-Took batteries out of the remote while picture was on and still went black.

-Switched to a different hdmi port.

-Reset cable/modem

Any suggestions? Just seems odd it will work fine then switch off.