Have you taken the coil packs out recently? Cleaned the stalks?
I did and a day or 2 after that I was having the same issues as you, seems like I cleaned them to well and now the spark seems to be are earthing across to the cylinder head before getting to the plugs!
To test this just remove all the coil packs and wrap some self amalgamating tape (or insulation tape but self amalgamating tape is better) down and back up the coil pack stalk and see if that makes a difference. It did for me
For 20 mins of work it is worth a shot