Somestimes when I am stopped at a stoplight, I hear a strange "pop" sound that seems to come from somewhere in the drivers side wheel well area. I does not happen all the time. Seems to occur more after driving long distances. What could it be?

Also, I am constantly having a problem with getting warped rotors. After 3k-4k, my car will start to shrudder when braking and my stops will be very jerky. Problem goes away when I replace the front rotors. Please help. Have gone through 3 rotors already. I think this problem developed after I ran my front left tire really hard into a curb last year.