I had them down pat with the metrenome and last night
This statement is the clue to the specific problem here.
When going from the practice room to the stage the environment is quite different. As David suggested in a previous post, get a recording and PLAY-ALONG.
It is a common frustration to practice and learn your parts well, then underfire, BLOW IT. If you get used to hearing all of the other instruments as you play-along with your recording then during the concert it will feel quite normal. I have many students for whom this procedure works well for.
We are simply trying to create and get used to the environment before we have to jump in.
Another clue is you saying "I'm mostly a jazzer". Good for you! But your experience is mostly "ear" and "feel". All the more reason to play-along and hear and feel.
Knowing the music is far more important than knowing the notes.