2008 Nissan Pathfinder noise when stopping or going over bu

Someone please help me! I am so frustrated. I got a 2008 pathfinder LE V8 and I noticed this sound a couple of months ago. No warning lights are on so I don't know what to make of it and it doesn't sound like the noise is from the engine. Its like it is coming from the left side. Anyway, the best way to describe the sound is. It sounds like one of those little toy lawnmower with the balls in it and it makes that popping/bubbling sound. Usuall when I am going over bumps or backing up. I also hear this "croak" sound when I stop. I have had a tire rotation and alignment. I have checked the inside, EVERYTHING. The dealership sent me home today and told me it was the wind deflectors, but I don't think so. I watched them on my way home and they weren't moving when I heard that sound, even though the adhesive is coming apart from the truck a little and its on the left side. I knew that was not the sound but I will go to have new adhesive tomorrow anyway at their expense and then take it right back b/c that sound is not coming from that. This is truly bothering me to the point that I just don't want the truck. Please, if someone has any idea, please help me.