Cathy, your story reminds me of a previous thread, where in that case it was an ungrateful daughter. The parents had lavished money and time on their daughter so she had never become independent. In your case a son who is over dependent, which he will be if you sort out all his problems, supply him with cars and money, and what other things before that?
Stand back and let him solve his own problems, find his own money and struggle and trip and pick himself up, brush himself down and start again. If he comes to you give him an understanding ear, a bit of advice and the occasional meal but no money, no cars, nothing but advice. Within a year he will be up and independent.