Try using a Blu-ray player with the TV or a DVD player that can output 1080p60. That will push the most amount of data you'll need (sans 3D) to see if the TV has issues. Most likely it's a cable TV infrastructure issue or the HD box itself, and possibly a source issue. What output resolution are you setting on the "box" with HDMI and component output?
And the pantaloon duck, white gooseneck quacked: Webcor, Webcor