I have an '04 xB and had my front motor mount replaced. There was excessive engine vibration and noise after that until I finally made the shop replace it after about 3 months. It's now been another 3 months and it's much quieter but I still have decent amount of noise and harmonics around 1500-3krpm that rival a 60hz sinewave. So my question is, what might have changed from the time I had the factory mount, the "new" mount, and the newest mount and what should I look for to fix this? The shop(Big O) insists nothing is wrong and it's normal; I'm done dealing with them.