I'm at a loss here.

Changed...

Distributor
Spark plugs
Spark plug wires
PCV Valve
EGR Valve

Ran Seafoam through intake manifold

When I drive and go WoT starting at around 2k RPM or lower in 3rd gear I almost always get a loud pop noise. Honestly at first I thought it sounded like someone hitting the engine bay with a baseball bat. But I think it's a misfire. If I drive slow and steady it's fine mostly but when going uphill for a long time it seems to get choked up and seems to want to stall and it'll jerk a little bit. But never actually stalls. I'll downshift and it'll be happy again.

Also on cold start (when it's freezing temps out) it'll run rough and even immediately start misfiring. Once warm she idles smooth.

Also the old spark plug from cylinder 4 was black and dry. I pulled the new one out after a few days of misfires and it is also black and sooty. Like carbon buildup I'm guessing?

Thoughts:

Since I basically did a full tune-up.... I think it's possibly injector related. It's weird because for several years it ran great and suddenly it's misfiring.

 

Bad coil pack

 

2001 Accord 4 cylinder didn't have individual coil packs like a 6 cylinder Accord. 4 cylinder Accords had the ignition coil built into the distributor.

 

Valve adjustment?