So this is quite a challenge: Reproducing that nice old medley Queen were performing during the Live Killers Tour.
So anyone may take the studio versions of Death On Two Legs, Killer Queen, Bicycle Race and I'm In Love With My Car and try to rearrange what Queen plyed live some 25 years ago ;)
They nearly never played a full version of Mustapha, but on many on the Live Killers shows they played at least the famous Mustapha intro.
But i don't really think it was before DOTL, as DOTL always was explaningly introduced by Freddie, who told the crowd what the song was all about.
You're right, they didn't play complete Mustapha on Live Killers tour.
But they played Mustapha in complete form live at least in the 1980 tour.
I just checked my MP3-concerts and in Glasgow 30-11-1979 they played Mustapha coupled directly to Death On Two Legs, which was followed by Killer Queen and I'm In Love With My Car.
I think they must have done that on more shows.