Had misfiring problem so fixed cracks in wiring near coil packs, helped a little but was still there, so did a little more digging around followed loom back and under the CTS area found this after removing insulation tape, so looks as if someone has attempted this before and bodged it with connectors.

 

 

So bought new coil pack loom replaced it and took it back to ECU. Couldn't get pins out of ECU so soldered the wires, heat shrinked and taped up, took about 4hours in total but was worth it.

Has made a big difference, tickover is smoother and the car feels a lot more responsive with no hesitation.

Good find. Its your worst nightmare finding stuff like that. I once took a stereo out of a car to find a nice previous owner had cut the standard block connector right off. Even the radio lead! My heart sank! Glad you got it sorted.