I had this same
problem when cleaning the spark plugs.
I would recommend taking the plugs out at seeing if they are still good.
Stick them back in if they are and look at the coil packs. I didnt click mine in properly the last time and that's why I was getting bad shuddering, check one hasn't come loose.
If not then your best bet is to leave it in somewhere
Replacing coil pack is about £40 i think