OK. I'm hearing a new and small sound of air 'puffs'. Here's a video. Fairly sure it is not 'mechanical'. (sorry to link out rather than embed)

 

If you want to find the problem don't wait for us to be of much help without you checking every square inch of exhaust system and then water testing for a vaccum leak.
By the way, those old factory plug wires are not helping your engine perform well if you have over 50,000 miles on them, need some 8 mm silicone replacements.

 

Hey Mike...looks can be deceiving. Those are 1yr old, 8mm Kingsborne wires. They are a bit messy because they don't fit in the factory looms as you probably know. I should make them a bit neater I suppose and put them in the looms I bought with the wires. I did do that to help routing back to the coil packs but didn't do any routing with the new looms alongside the valve covers.

Please tell me about water testing. Are you talking about spraying small amounts of water with perhaps a tiny soap additive to check for bubbles to check for vacuum leaks?

 

Time for me to get new glasses. As for the noise, what I hear or what it sounds like to me is a pulley bearing noise.
If it were vacuum, you would have a possible high idle, rough running and certainly some fault codes, if it were an exhaust leak, you would have a soot stain on the header, exhaust pipe or gaskets.
Don't worry about it being a vacuum leak without codes.

 

Thanks Mike. I'll do some more poking around.

If anyone else has any ideas, shoot them in. Watching a video is certainly not the best diagnostic tool but I'm all ears.

 

Reviving this old thread.... The answer is.... the spark plug was not seated properly.