What is the episode to Family Guy where he goes into the past?

"He" ... exactly who is the "He" you speak of ?

Brian, Stewie & Mort go into the past in Road to Germany.

Peter & Brian go into the past in Meet the Quagmires.

Stewie, Brian & Bertram go into the past in The Big Bang Theory.

Stewie & Brian go into the past in Back to the Pilot.

Stewie travels into the past (& future) in The Untold Story.