2003 Honda Civic EX (~230,000 miles) has been giving me misfire codes for a while, mostly on cylinders 2 & 3, but sometimes 4.
- P0300 Random cylinder
- P0302 Cylinder 2
- P0303 Cylinder 3
- P0304 Cylinder 4
Took it to mechanic and they couldn't figure out what's wrong, they see the codes, too, but didn't see/hear any misfires, and said I should keep driving it and see if it gets worse and then it will be easier to identify. Any advice on how to identify the cause? (It has P0420 catalytic converter code for a long time, too. We've pretty much given up on fixing that.)