Shouldn't have any issues with vibrations. I would take it back to whoever mounted them or somewhere else to give them a shot at getting them correct. Vibration at those speeds would definitely make me like the setup less.
Thanks. I just got it about a month ago, stock, and have made a few changes to it so far. I leveled it with Bilstein 6112 on the front, they are fantastic and am still stock in the rear so far. I plan on doing FJ rear spring swap when I can find a good set of used ones.