Mercedes E500
 

It's laying down like a dead dog. I'm helping out a friend and could use some advice if you've run across a problem similar. I have changed out the air pump on the front left, but have not gone any further. The back left looks suspect, and the owner drove the car in to the shop disregarding the mechs recommendation to have it towed. Who knows what else was torn up while he nursed it in. I know to look for the air leaks with soapy water and what not, but was hoping that I might get a few suggestions. It's a 2004.

Thanks in advance.