What is the name of episode where stewie vaults in living room?

You're likely thinking of the iconic scene where Stewie Griffin attempts to vault over the couch in the "Family Guy" episode "Road to Europe".

This episode aired on November 12, 2000, and features Stewie attempting to emulate the legendary Olympian, Bruce Jenner (now Caitlyn Jenner). He fails spectacularly, ending up with a broken leg and a bruised ego.

This scene became a popular meme and is often referenced in discussions of "Family Guy" humor.