I have a 1999 Accord EX with the 3.0L V6 and 136k mi. Here's my situation: Pulled codes P0300, P0302, and P0303. I've just replaced the cap & rotor, confirmed good spark on all plug wires. Some carbon deposits on all spark plugs (Denso KJ16CR-L11, 12k miles on plugs)

Compression
Approximately 180psi on cylinders 1-4 and 6
80psi on cylinder 5

From searching, most of the people with misfire issues replace the cap, rotor, wires, and plugs to start. I think mine are in good shape. I'd appreciate some diagnositic advice before I do any more tinkering or spend any more money. Thanks.