I race mainly offroad but at the last race we had a rain delay for about an hour and a half... then I was up first... I'll just say I've had better qualifiers! Excluding that day, one or two does help smooth out a little twitchiness.
My very best run I've ever had was with a severe hangover. Puked in my car on the way to the track, then TQ'ed by about 13 seconds over a 30 car field.