I was driving down hwy and drive stopped working. coasted to side of road and had no gears and 4wd wouldn't move until was put in 4wd and low range together and high speed rev took off now will go forward but no reverse feels like it wants to but just a throb. fluids are good and no noise. what do you all think? Possible sensor. torque converter. seals. vacuum. heard several things just don't know where to start. Any help would be appreciated.