I have a 1983 Mercedes Benz 300d. I was driving on the highway and took an off ramp so I slowed down, when I tried to speed back up it wouldn't do anything. I had my foot to the floor and it wouldnt speed up at all. I had to coast to the parking lot. After that it wont start again. It tries but it wont. Its been making a sound of metal hiting metal for a couple weeks but now theres another sound that everytime it tries to start it sounds like something metal is swinging around hitting the cover. I was told it might have to do with the timing chain. What is wrong with it?