I have an 04 Murano SE w/87,000mls. There's been a flopping noise coming from under the car, mainly when I ease off the gas. Initially, the Nissan dealer thought it might be a wheel bearing. When they ruled that out, they did a tire rotation. When the noise continued, they said we needed 4 new tires. Which we got. Unfortunately, the noise is still there. It sounds a little bit like a softer version of when a car rolls over speed bumps on the highway. Could it possibly have something to do with the accelerator or drive train since it acts up when I decelerate?