roughness in cylinder 1 P38 thor engine but no fault code??!!!, diagnostic screenshot..

Suddenly my pet develop vibration and rotten egg smell from the pipe. after checking and replacing the spark and HT wire on the cylinder 1, nothing change... I keep the roughness
in cylinder 1 and NO FAULT CODE. do not know what to do..

here is the diagnostic screenshot





please advice.

Thanks

Do all the plugs look the same colour?
It could still be a bad plug or lead.
You never get 100% fitting on every cylinder every time, that's normal. There's a rolling threshold before it trips a misfire code. 5 isn't ideal but it's not really bad.
Have you done a compression test?