How to diagnose this misfire?

2007 Honda Odyssey with VCM-1 system, I assumed that was the issue so took it off and cleaned it but it looked fine before, no luck. The owner already replaced plugs and coils and still has the same issue. Hard misfire at idle with blinking check engine light and limp mode so it won’t go over about 3500 rpm.

2007 Honda Odyssey with VCM-1 system, I assumed that was the issue so took it off and cleaned it but it looked fine before, no luck. The owner already replaced plugs and coils and still has the same issue. Hard misfire at idle with blinking check engine light and limp mode so it won’t go over about 3500 rpm.