1999 SL2 won't start

I own a 99 SL2 with 134,000. I had noticed that it seemed to be missing when I was driving it. Then I got in it one day and it was terrible. It didn't want to go, it seemed to be "chugging". My dad took it home with him, and he has replaced the CPS, ECTS, Spark Plugs, Coil Pack, tested the fuel pressure. At first it would start, then when he put it into gear it would die. Now it won't start at all. I need some suggestions! Thanks!