If you have a j4 ecu and harness just use it. Unless you think there is something not right about it. Im not sure what would cause it to flood out other than the ecu, wiring or injectors. Bump cause Im sure someone else has had this problem.
Heres the j4/j5 pin out and some other useful info. I hope this helps a little bit.
http://skylineking.com/info.html