Missfire, loosing spark irregularly

[Ram Air IV]

I have a LQ9 (6.0 L) in my Firebird -68. During the winter I have made a new harness. With the new harness the spark fails say 1 of 20. This occurs irregularly on all cylinders. I have measured the voltage at the coil and it is 14,5 V with the engin running. Any clue ? The engin run perfect before I changed the harness.
Magnus

[Baldric]

would say somethings amiss in your new hardness did you follow the schematic properly ?and have correct wire thickness for all pinouts ?

[Ram Air IV]

The schematic I have for the LQ9 2002 did not correspond to the harness that belong to the engin. I have made a copy of the old harness (but with longer wires) and yes I do belive that I have missed something. Most wires are either 0,35 or 0,8 mm2 according to the schematics and in my new harness I have used 0,75 mm2 for all wires.