Rep Power: 0

I have a 2003 EX with 195,000 miles. The scanner is showing misfires on 3 and 4 along with miscellaneous misfires. I suspect a small oil leak from the spark plug tube seal on 3 as there is a little oil around the base of the spark plug on the coil side. Spark plug 4, and 3 to a lesser extent, have what I assume are carbon build up. All plugs are only a few months old, Denso iridium.

I want to do a compression test and a top down leak test, but I'm afraid to run the engine long enough to get to operating temp with how bad the misfire is.

Attached image shows plugs, numbered as I understand them to be numbered. 4 was scraped with my thumb nail to see how hard the black stuff is and sprayed with carb cleaner one time.

 
Rep Power: 224

I would suspect 4 is your issue. 3 follows 4 in the firing order so it may be unrelated. You could initially try swapping plugs and coils around to see what the misfires follow. Take the plug from 4 and move to 1. Take the coil from 4 and move to 2. See if the misfire switches to one of the other cylinders.

 
Rep Power: 511

Just being pedantic. Isn't it 1-3-4-2?

But yeah, cyl 4 is def the culprit. For the plugs on cylinders 1-3, are they white or like.. toasted marshmallow tan?

 
Rep Power: 224

I had it in my head that it was 1-4-3-2. Thinking about it now, that doesn't even make sense. You are correct @xRiCeBoYx

 
Rep Power: 0

I've put in the same type spark plugs it came with, Denso platinum. I've swapped coils 1&3 and 2&4. It's still running rough at idle and lower RPMs, but smooths out around 3k. No new codes, so I can't determine the cylinder that way, exhaust note sounds like it is missing combustion on one cylinder though. Putting my hand in front of the exhaust, I can see small black liquid splattering on my hand, like a mist. Think droplets like the size from a spray paint can, but no where as dense. Like it took several seconds to notice it on my hand.

 
Rep Power: 224

Does it have EGR? Clogged EGR runners in the intake manifold can cause misfires. Maybe the actual EGR valve as well.

 
Rep Power: 222

Doesn't set codes either if i remember correctly

 
Rep Power: 0

I'll pull and clean the EGR valve tomorrow. I'm not familiar with cleaning the runners, so I'll have to look that up. If you know a good tutorial, feel free to link it, lol.

 
Rep Power: 222

Take the manifold off, clean, reinstall. Make sure you use the gasket that has the holes for egr

 
Rep Power: 224

The runners are in the thin aluminum part of the intake manifold, not the large plastic part.

 
Rep Power: 0

Intake or exhaust?

 
Rep Power: 222

Intake