general problems of the 1998 Oldsmobile Bravada

I purchased a used 1998 olds Bravada. It has been an ok car except. The heater/air conditioner doesn't work properly. My dealer says you have to switch it back and forth from heat to cool in the dash somewhere (my question was, what is the thermostat button for then???). Also, the transmission or motor at 3000 rpms cuts out bad and jumps and could cause an accident if you are in the passing zone when this happens. Also, the dimmer switch doesn't work anymore. The windshield wipers do and the signals do but not the dimmer??.

Vehicle has a complete loss of power while driving. It happens numerous times without warning while driving to work 3rd shift 55-60 mph on a country road. . . Vehicle would suddenly shut down. With no lights, power steering, ect. . . I would have to try and pull over in the pitch black of night. After about 20 minutes it would start back up and on I would go, praying it wouldn't happen at the curves. After a couple of years of this and nobody having any answers, my husband discovered it is a connector in the steering column that gets corroded and he has to clean it. As long as we clean the corrosion off of the connector about twice a year, the vehicle does fine.