Can anyone tell me the episode where Amy pulls the skin under her chin out above her chin? I saw this years ago and have been trying to figure out which episode it was from since then!

This episode is the one where Marie finally gets glasses. The family noticed her vision was getting worse and worse, and when Debra was about to use a fork, she noticed it was dirty. Marie says that there are no dirty forks in her house, and when she notices it really is, she walks off in shame.
From there, she starts noticing things about the family that does not sit well with the others. For Ray, it was the grey in his sideburns. For Debra, it was that she had thin eyelashes. Robert got botox injections because of wrinkles, and Amy pulled the skin down from her chin.
In the end, Frank breaks the glasses after Marie says they have a loveless marriage.

The episode is called Marie's Vision. You can find it in Season 7.