Code 456 has nothing to do with engine performance. That refers to fuel vapors expanding in the gas tank, then being stored in the charcoal canister. At certain times, the Engine Computer opens the purge valve so those stored vapors can be drawn out and burned. That entire system is monitored for leaks to prevent hydrocarbons from being released into the atmosphere. Chrysler does that by pumping the system into two pounds of pressure, then watching how long it takes for that pressure to bleed off. Code 456 refers to a slow leak, unlike that of a lose gas cap.
The injector circuit code is not one I've worked with before. I only know the computer monitors the electrical integrity of the circuit, and it can read the resulting current wave forms to interpret how the injector is operating mechanically. Chrysler has very little trouble with their injectors, so given your description of the symptom, my first suspicion would be a wiring connector is being tugged on when the engine rocks during acceleration, and an intermittent break in the circuit could cause jerking or rough running. I actually had that happen to my old '88 Grand Caravan about three days after I stuffed a different engine in it. Three injectors stopped firing intermittently, but only under hard acceleration. Unplugging and reseating the plug for the engine wiring harness solved the problem.
You might be able to make the problem occur by flexing various harnesses while the engine is idling. You'll be able to hear the misfire if one injector stops firing. If nothing is found, switch this and one other injector, erase the fault code, then see if the code sets again for the same cylinder or the one you moved the suspect injector to. If the code moves to the new cylinder, it's pretty sure the injector is the cause of the problem.
Thursday, May 18th, 2017 AT 7:55 PM