I have a 2006 mercury 90hp 4stroke efi that has a mid section whine at idle in neutral. From what I’ve read this is a common problem, but haven’t found a solution nor do I know exactly what’s causing it. My understanding is it’s a vibration from the drive shaft on a bushing. Any thoughts or experiences would be appreciated. I also have a gear chatter at idle when in gear (forward and reverse) but the slightest bump in rpms and it’s gone. Binnacle controls are well greased and the cables are new. Thanks Cody.