The vehicle also acts and feels as if it's going to stall out. These issues started suddenly.
My car has 71000 miles.
My car's transmission is unknown to me.
Hi - the "Reduced Engine Power" message is an "aggregate message", sort of like "Check Engine", which can be caused by both engine or transmission problems. Engine performance is cut back, in theory to avoid further damage. First task is to look at problem codes using a code reader. This should provide real insight in to the specific problem causing this condition. I would recommend a Check Engine service by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.