Software problems of the 2007 Toyota FJ Cruiser

I own a 2007 Toyota Fj Cruiser with a manual transmission. The throttle management software is a joke at best and dangerous at worst. The vehicle engine rpm will not go below 12-1800rpm when the vehicle is moving unless the speed is somewhere below 5mph. This can be very annoying at times and dangerous at others. Driving on ice, towing a trailer, driving in hilly terrain. There is no engine braking available at any speed above 5mph. When the software does finally close the throttle completely it does so abruptly causing a jerky condition that can lead to loss of control on ice. At 20mph, for instance driving in a school zone, the throttle cannot be set to maintain a steady speed. The vehicle alternates between accelerating and almost complete throttle shut off. There is no in between. I have seen this same behavior when driving off road in steep terrain. Not only is it annoying but it is dangerous. I have had the vehicle to Toyota twice and they claim it is normal for this model and that there is nothing that can be done. The other thing that it does is hold the last rpm for several seconds when shifting between gears. Not so much dangerous as annoying and causes excessive wear on driveline components and is also extremely wasteful of fuel.