They appear in a fictitious Christmas special, KISS Saves Santa in A Very Special Family Guy Freakin' Christmas and they appear in Road to Europe. Gene Simmons alone appears in Don't Make Me Over
Dial Meg For Murder
Christmas Guy.
Stuck Together, Torn Apart
Your question is vague to say the least but you might be describing Season 5|Episode 7 Chick Cancer when Brian tells Stewie "it's not your fault"
Its the episode where Stewie and Brian are on a Trip to Aspen, Co to get Rupet back called Road to Rupert.
The episode where Brian, Stewie and Peter sing "The Freakin' F.C.C." Is PTV, Volume 4 episode 1.
family guy season 8 episode 15 "Brian Griffin's House of Payne" total episode 141
Brian & Stewie's Emmy appearance & performance wasn't part of any Family Guy episode.
Saving Private Brian
Saving Private Brian.
All of the "Road to" episodes are primarily Stewie and Brian centered episodes, also of the episode titled Brian and Stewie
Season 3.
The evil Stewie clone does it in The Hand That Rocks the Cradle
Road to Europe
Season 6 | Peter's Daughter
No.
Stuck Together, Torn Apart
syrup o Epicac
S07|E01 Love, Blactually