Cecil,
You are advised to slip the transmission into neutral when you are at a stop light, or stopped for more than a minute. If you don't do this, the transmission will overheat.......switching to Transcynd will help enormously.
Your brakes need to be serviced. It may be that the rotors are glazed.......from light use, or little use. Glazing can be removed by resurfacing the rotors.......or by a light application of emery paper in circular motions, if glazing is not too bad.
Either way, you must be safely able to hold the coach on the service brakes even on steep hill.