All great ideas about the nature of the problem! We took the car for evaluation and, as soon as it was going up on the lift, we all saw the problem. It was indeed a plastic bag wrapped around and melted on the exhaust pipe. Our mechanic said we were lucky it had not caught fire.
So, it is fixed, they changed the oil as long as we were there, checked the brakes and all is well. Soon that subaru will be hauling my trailer full of flowers, plants and veggies to spring farmers' markets here in MA. Yes! Spring will be here soon.
J&L