I have the exact same unit. Things to look for:
Start by looking for ANY signs of roof leaks. Any soft spots on the sides and any ceiling irregularities are clear signs of water penetration.
Check all of the appliances and accessories.
Water heater, stove, furnace, refrigerator (both AC and GAS opperaton), leveling system, electric stairs...
Take it out for a drive around the block and verify brakes and coolant temperatures.
Oh, did I mention roof leaks???? Yes, that's probably the most common issue with the fiberglass Air Stream motorhomes.