Hello Sorento owners,
I aso have a 2003 Sorento LX that has the same noise and very slight vibration between 110 and 120. I have complained about this to the dealer since new and they kept saying "once we rotate the tires it will be OK". Well 2 years later its the same, they replaced a joint in the drivetrain but it did not fix the problem, and refuse to look at this problem any further. The dealer now wants me, at my expense, to take it somewhere to have a Road Force wheel balance. I have talked to the company (a Ford dealership which also ownes the Kia dealership) that has this machine and they highly doubt it will come to any resolution, other than me out $100.00 plus tax. I have seen many Sorento owners posting this exact problem on different sites and also Consumer Reports list this as a known problem but Kia refuses to deal with it. The solution that seems to correct the problem, from what I have read, is to have the drive shafts balanced or replaced by a qualified garage. Most of these garages also balance engines.
I still love my Sorento, its a very tough 4x4, very comfortable and enough power for anything I have put it through.