I have a 1994 Sunbird V6 that is Leaking Coolant from an Elbow coming out from the Firewall. How do I stop this?

Aside from disconnecting your heater hoses, the only fix is to replace the "heater core". The "heat" function of your climate control system relies on heated engine coolant to work. The small elbow that you describe, is most likely the condensate drain. The "heater core" and the "evaporator core(for the a/c)", are located beneath the dash assembly in an enclosed housing. The "heater core" should be serviceable without removing the complete housing as with some vehicles. I hope this helps