Holy Error Codes MZ.... I too would try the reset and see if it comes back. I did that on a Leaking injector code, no smell, no visable evidence. Then move onto the 1, 3 and 5 injectors that you can get at without removing the intake... It could be as simple as a loose connection. Clear the ECU then if it comes back again, its on to 2, 4 and 6...
While your in there, it would also be a good idea to swap out some old coolant and Vaccuum lines....
Depending on Milage, now may be a good time to upgrade/replace injectors