Hello everyone:
2004 G35 Coupe w/98k miles
Here's my issue: A couple weeks ago I noticed a subtle noise while idling through a parking lot - its almost so subtle that one might not think much of it, but since I have been driving the car for almost 6 years, it is very apparent to me!
My best description of the sound: Its almost like a vibration but you cant feel it but only can hear it. My initial impression was passenger side engine bay but I cannot hear the sound outside of the car. I almost thought it sounded "exhausty" for a little while.
Course of action: I have been doing maintenance myself but never did a full 90k service so I took the car to a local shop to have them look at it and see if they could figure out the noise. Since I was already there, I had them do the 90k service and change all the fluids and drive belts. They were unable to find the source of the noise but the owner said he could hear it (so its not just in my head). So the service and new belts did not fix the noise.
Today, I seafoamed the intake, crank case and fuel system, then replaced the plugs. I did find the dreaded valve oil leak in the the #5 cylinder, but it is not leaking profusely so I think I'll wait a few more miles before doing the valve seals. So new plugs and a thorough cleaning did not fix the noise.
I spent the last few hours searching this forum and have found people had some luck with a similar symptom by changing the fuel dampener on the passenger side. I am ready to buy the part but would like to get an opinion whether this is a good next step or if anyone has a better idea. Also, anyone have any tips on how to change this thing?

Thanks