Curious, did you ever have any luck figuring out the issue? I'm having the same problem. I had the majority of my front suspension replaced, basically exactly what you listed, and when I picked it up within a few days I felt a slight shaking when hitting 20mph...everyday since, it's been worse. But like yours, it's not always as bad as it was before. Now it starts around 10 and continues til 45..and even has a slight shake higher than 50. I spoke to one person who said to check the motor mounts and I'm doing that in a few days.