I've put a different ecu on my apy s3,I've modified the wiring slightly to get the ecu to work,it ticks over fine and revs up fine but when you drive the car it gets to about 3500 rpm under load and misfires but if you drive it gently it will rev through fine,does this sound like a coil pack problem as I've read that the coil packs can sometimes play up with a remapped ecu