ok try this old hack, at night go to someplace dark, carry a bottle of water spray without. And with the engine running spray water mist around coils, plug wires and if there is a short you will see electricity arcing and sparking. If this doesnt show any conclusive results.
With the car started disconnect and connect every plug wire, if the missing gets worse you know that one is working and put that back in. If you reach a coil where disconnecting and connect doesnt make any difference, then that is your suspect circuit. Either that coil, wire or plug is bad.