Random Vibration

I am at a loss on this one.



My husband and I have a 2003 Ford Focus. This car has served us very well and are up to date on it’s regular maintenance.



We noticed an increasingly loud noise coming from the front passenger’s side tire. This developed over the course of maybe three months. The day before we brought the car in for diagnosis we acquired another issue, a rhythmic vibration that starts 60-65 mph then comes and goes randomly after that.



The sound turned out to be a bearing and we had that fixed, the sound is completely gone. But the weird vibration is still there.



The vibration only starts at around 60-65 mph. I can drive the car for hours under that speed and the vibration never comes out to play.



But as soon as I accelerate to that speed I get a huge rhythmic vibration. When it first happened I thought I had a flat. The thing that confuses me the most about this whole situation is that the vibration is not constant. I can accelerate to and maintain speeds above 60 mph and while the vibration will present itself initially it will completely disappear and then reappear randomly from there on.



I have been unable to link the vibration to any variably that I as a driver have control over. It does not appear to be linked to gas pedal depression, steering, or braking. The alignment was done when the bearing was fixed so I know it is not linked to that.



Does anyone have any idea what might be causing this?

I’d rotate the front tires to the back and see if anything changes. It’s a cheap place to start.