i would get a few maps from the junk yard and do some swapping first.If and intake valve stuck open you would have a back fire.If a exhaust valve stuck open you would have popping noise in your exhaust.Plus if a valve sticks open is usually hits the piston and will cause a permanent misfire.

If a map gos bad you a/f ratio gos to shit runs lean or rich at different rpms causing misfires.

Do you have a turbo,a/f controller.