Misfires

[Gelbster]

The first thing to check is that you fitted the correct parts. Both the plugs and coils are different in different engine size/year. Some differ by just 1 digit !
Next the connectors on the coils. Unless you lubricate the cover/sheath and push it back to make the connector 'click' into place - that may be an issue.If you don't do this you may have poor connection at the coil and you will swear it is perfect.It isn't.
If you mean Bank 2 (left?? that will be confusing) check the wiring harness. Almost impossible because of the congestion - but use a small ,powerful LED Inspection Lamp. You are looking for rat droppings and maybe loose ground by Cyl #4(brown conductors on a stud).
Next stage is the flailing - swap #4 plug and coil with #1 - does the problem follow? Suggest you find the dwg of the Bank/Cylinder layout to make the diagnostics unambiguous.Using Left/right ,front/back will lead you up the garden path.It really confuses the 996 guys.
Good Luck !