Hello,
Question on a 2001 S40.
I replaced plugs, wires, and one coil (Cracked). Still have codes for the misfire 303, and 304.

Symtoms:
-Rough idle.
-Hard to start randomly, sometimes once sometimes several times. Cranks strong sometimes it feels like it is not firing. just cranks.
-Sometimes a drop in rpm almost to a stall but recovers.

She runs great once we're moving, more responsive after the coil change. Wires were about a week ago, plugs several months ago.
Spark plugs are gapped correctly, not damaged, have normal wear.

I have read countless other forms and have not been able to find this solution.

 

Try switching the injectors to cylinder 1 and 2 and run it. If the misfire moves then you have found your problem

 

Finished this morning. Put 3 and 4 fuel injectors where 1 and 2 were.
They looked very clean.
If that's the case, how do I post images and a description for others in the future? It was not too hard.

 

Still have codes for 3 and 4 after changing the fuel injectors over.