i have a 2000 gsr this code just poped up recently for me (p1399) i dunno what is it but the car sounds like a subaru impreza.at idle its sounds like that but when i start driving it its seems fine. it seems no power lose only at idle. it seems like the no.4 cylinder is either not getting spark or fuel. if any one would know what to do please help and thx alot.

 

Here is a thread with that code:
https://honda-tech.com/zerothread?id=1962862