Car shaking/vibrating Issue

Got_Z

Greetings.

For the past year or so I've an issue with the Z. The steering wheel shakes/vibrates when braking. Issue started around 10k miles so I had my rotors resurfaced which helped up until 14k miles it was back. At the point I decided Im not paying for resurfacing over and over again.

At 24k miles the shaking/vibrating got too much to handle so I replaced my brakes and rotors (stoptech street and stoptech slotted) as well as got SS brake lines and some DOT 4 fluid.

Now after 2k miles the slight shaking is back. I have taken the car to the dealership on Friday with this issue. I got a call this morning from them stating they worked on it all day and have been unsuccessful identifying where exactly the problem is. They told me they're calling Nissan Corporate and will let me know what is going on by Monday.. (not sure what that means)

Any ideas as to what else it could be?

***Side Note: Tires are in good condition with proper amount of air and alignment.***