I start my car once in a while during winter, the other day I started the car and went for a ride. Everything sounded and felt normal, today I started the car and it was quieter. I took it for a ride and it's even quieter inside. It feels like it has the normal power but just quieter. I did notice when I first started the car, the right side tail pipe was cold exhaust and the left was more powerful hot exhaust. Any thoughts?