My mother has a 2002 Stratus and it has over 181,000 miles on it. She had it for over eight years and it now makes moaning sounds upon startup. The noise tends to come from the engine. I also hear it when she steps on the gas pedal. What could be causing this noise?
Time for a new belt is my guess, sure it could be a tensioner, sure it could be a power steering motor. At 181 k you are doing well, I do not know your maintenance history but it might be time to look at the manual and make sure all suggested maintenance has been performed. Leave it overnight at a qualified mechanic and they should have no trouble isolating the source in the morning.
Since the Stratus has a timing BELT and the mileage is about time for the second change, and it is an interference engine according to my resources, I would go with a new belt, tensioner likely water pump etc. Failing to do so could cause you a whole new engine.