09 Legacy

I think the key would have to be that it only happens after a good amount of highway driving and for some reason is fine once I let it rest for a minute or come back down to city speeds.

Not sure about what the dealership used for CV. Issue is now coming up 1-2 years after the repaired happened. Before it was an issue of slow tight turns causing binding and slipping, for example when pulling into parking spots. No check engine lights, brakes or turning doesn't appear to change anything. Just happens as I am driving along the highway and pops up randomly as I am cruising along after about 30 minutes. Just driving along a pretty flat straight highway, nothing out of the ordinary. Tires are only a year or two old and have some inconsistent wear, but nothing too bad I don't think. Back during that repair I did just recently realize that they put one of the "directional" tires on the wrong way but not sure how much that hurts things.

Only after driving 20-30 minutes on the highway out of nowhere the front of the car will start shaking significantly. Still happening in neutral while coasting at speed and during shake pushing the gas pedal seems to cause little to no speeding up. Don't think it is in steering wheel and is more in engine I think. Enough shaking to make me pull over and shut down. And then when I start back up and get up to speed it seems to be ok again. Talked with local dealer and he thinks it could be bad wheel bearings given it needs to warm up before being an issue. Any thoughts anyone? 2009 Subaru Legacy, non turbo, 101k miles, already replaced CV coupling and some other maintenance. Thanks Josh