most obvious considering the fact that it idles rough would be that an injector died or there's a loss of connection to one of them, but based on description of the code
27 Injector 3, and/or 4, and/or 5, and/or 6 output driver does not respond properly to the control signal.
would mean that the driver for that injector (electronic device within the PCM) malfunctions - not sure if that includes the faulty injector or no conection - i assume based on description that the PCM monitors the output of the injector driver line and detects that there is no ground signal there, the positive wire is always at 12v when the engine is running. Again, i have no idea if this includes faulty injector or loss of connection, i hope it does so you don't have to replace the PCM.
You can replace the injectors with the old ones and see what the result is, or you can also see if the injectors get ground on the driver wire when you crank the engine (the 12v is green/orange, not sure what the color of the command line is but is the other one) you need a multimeter with fast response, the ones with a needle are better for this unless you have an expensive one, measure the voltage at the driver line, when you put the ignition contact on you will detect a voltage (start with the 20v scale) and when you crank it you should get ground (it would drop to 0v for a quick moment). I would suggest to unplug the coil if you do this so it wont start, but be aware that you might flood it. If you have an oscilloscope you could also monitor that at idle and see if the ground signal form is constant. If you have n old injector that you dont need and an injector connector you can make a tap-in and put it in between the connector and the injector on the car, that way you dont have to splice or use a needle or any other tricks to measure if you do that with the engine running.
Seems that since you have the old injectors would be an obvious choice to try with the old ones, but again i am not sure if that error code would account for a faulty one - maybe someone here has experienced that before and can help out with some info
