I am working on a 550 SL that was running and when it was stopped at a redlight the engine died. The guy that was driving said that he thought that it had run out of gas and he pushed it to the Gas station and put some in. This did not help and had to be towed to the shop. There is spark, and fuel is on the plugs. The Dist cap and button was been changed by the owner because it looked burnt. It is showing to be in time. The owner also checked all of the fuses and they were good. We are pulling our hair out. What are we not seeing? I am sure that it is something simple. Thank You, and God Bless.