Right so ive got my car all mapped and am happy with the way it drives etc, but ive got a small misfire at around 3500rpm. Tried and tested all the usual suspects with no luck, so it was suggested to me to try switching the ignition triggering to rising edge as i was on falling.
So i tried this last night, and its cured the misfire or so it seems. But now the car idles like shit and is lean across the whole map except very low rpm/idle where its rich. I spent some time playing with the map and it now drives better, ive also pulled 5degrees from the whole on boost section of the map for safety. So what i want to know is.

Why would/has this cured my misfire?
What effect has it had on the ignition timing?