I'm voting for air in the system. Definitely interested to see what it turns out to be!Something that I did notice was that it doesn't always self level after stopping, even if parked on my sloped driveway. I would say 50% of the time it does not. The ahc spheres are genuine Toyota fitted by Toyota dealer, the ride had gotten harsh before replacement, after replacement it was smooth for a short period. Its not harsh all the time, it seems to come good and then goes rock solid to the point where it's shaking everything in the car.
Did you really find some for $800? The cheapest I can find is more like $1000.