1998 Dodge Ram 4X4 Quad 5.9L Auto. When
Mr. dodge ram, with the 46re trans the pcm needs a signal from the tps sensor to monitor throtlle opening, accel and decel, what has happened the tps has a worn out spot in cruise area, hence the down shift, uphill is fine because your past the worn out spot, replace your tps sensor, its mount on left side of throtlle body , 2 screws, 1 connecter, and its out, when done turn key on, eng off, step on gas pedal 6 times slowly, then turn off key, this will help set min tps setting, GOOD LUCK RDJRP