Help please, I have a 1997 Boxster 2.5L that I recently replaced the head gaskets on. I have reassembled everything but I have no spark on the left side of engine (cylinders 4-6). The engine will start and run (rough) but its only firing on the right side (cylinders 1-3). I am assuming that its an electrical problem but not sure if its a bad connection or a bad ground and I don't know where to start. Any help or advice would be greatly appreciated. Thanks Matt