Nissan USA's attempt
Today I made the drive over the pass to Idaho to meet Mr. Nissan. He was the service technician that they sent in from Washington to evaluate the MO. After taking a detailed history and a test drive, he sent me shopping and did some evaluating. A few hours late, he came back with an answer: TIRES.
Can you believe it?! What I said to every dealer from March onward was that this problem never existed until I got new tires. Apparently he switched out the tires on my MO for a new MO's factory issued tires (Goodyear Eagle's that I had before this) after driving the new MO to note the vibration issues it had on the same road we had driven. He claims after replacing the tires, the issues at high speeds - dramatic shaking in the front which has now moved to the rear since last update - was gone completely, and that while the steering wheel still vibrated a bit (side to side shimmy), it was dramatically better and nothing like before. I don't know because he swapped the tires before I returned so I could not drive it. He also bolted as soon as they called me so I couldn't even talk to him in person - so weird. Interestingly the mechanic who was working with me at this dealership the whole time did attempt the same fix, but he did not notice any difference. This was before the new axels however and Mr. Nissan said that he also cleaned the wheel attachments (not quite sure exactly what he said here but that's the gist) to ensure a better fit. Mr. Nissan believes one of the tires was harder than the others but this Nissan dealership doesn't have a Road Force machine so he couldn't get a RFV reading.
So now I've got a complain into Michelin and I'm supposed to hear back from the supervisor I spoke with's supervisor because I don't want a Michelin or Uniroyal or BF Goodrich product if they make them! Clearly they have a quality control issue if I got not one but two bad sets of tires. I'm hoping I can get my money back - I asked for a one time courtesy refund, so we'll see what happens.
But now I'm back to needing another set of tires! At this point, I'm tempted just to get Goodyear Eagles again because I know they didn't do this before since I've had two sets of them. I wanted something different because I didn't like how they wore, but now that I know that my control arms were bad, that's what most likely caused the cupping and the uneven wear. Since I've got new ones, maybe I'll be safe!
Just wanted to give everyone an update and to say thanks again for all the suggestions. I'm still holding my breath that the tires will fix it, because I've heard it all before that they know what'll do it!