If you are running a 1g long block ina 2g without dsmlink or some type of standalone u are going to get random misfire codes. When u get this code your car will run on 2 cylinders. Changing the cas is not going to do a damn thing.
You can fix this by a buying a dsmlink or standalone or b when u get the code stop the car. Turn it completely off and turn it back on. Code should go away for a little while but it will always come back.
As far as your fuel cut issue I have no idea what's going on but I would start by turning the boost down . If I were you I would also remember that I am running a 16g not a t25 on bone stock 450 injectors with obviously no fuel control or no logging software.
