TriX5
2006, 4.8is, 78K miles.

Yea so I was 95 percent sure that the mounts were shot they day I got the car. Not completely shot, but in need of replacement. My unfamiliarity with the car led me on a chase for other issues before tackling the mount. About a week ago, I was 99 percent sure the mounts are now completely done. I feel like I should have followed my instinct and changed them, but I was hesitant since there might have been other issues at play. There weren't. I did preventative maintenance anyway, but nothing helped this specific problem. New plugs, cleaned maf, cleaned TB, new fuel filter, new air filter, oil and filter. Nothing helped the above.

So since day one, the test that has never failed me is the vibration, more vibration in drive, and vibration in reverse. Vibration in P and N much less but there. If you turn the AC on, the vibration in every gear becomes 70 percent less. This is exactly the same diagnosis I have had with every broken mount I ever dealt with. The AC on test is what always settles it for me, especially since there are no codes or anything. To re-enforce my theory, I started paying attention to delay of the line. You press the go pedal, but there is just that slight delay before the car moves. Shifts seem like they rock the boat ever so slightly.

Read last reply. I have a theory on some stuff.