Odd missfire

A couple of times now ive had a bit of what i would call a missfire as the engine revs down to idle. It's all a bit weird and irregular, but something aint right. It almost sounds like it's one cylinder down, the 90 shakes very lightly then it settles again.
Anyone seen anything like this before?

Injector harness......

I agree with LandyBandy.

Pull the red plug off your ecu and have a look for signs of oil contamination.