Hi i have a 2007 ml350 i started to notice that my front wheels lower itself occassionally after parking. I would hear a hissing sound from the front left tire and both front tires would lower itself. It raises itself back up once i start the car and on occassion if i move my car a little bit forward or backward it wouldnt hiss and the car stays raised up. My cousin said it might be the strut and he thinks that as long as i wait for it to raise up before driving it it wouldnt cause any other problems. I canvassed and it would cost me 1700 for one strut replacement... Help pls