I would start there .. they are under each coil. Change them
[ cheap] and check the plugs at the same time.
PS -[ that engine like Bosch F8DC4 Copper core ONLY, and again ,cheap].

Also, i would look and see if the OVP is the original.. if so [ made by Siemens], change it to the new replacement.
Do an OVP search for part #s..