1985 Pontiac 6000 Engines Knocking

For the past couple of days, my engine has been making this knocking sound when I start to drive, it also keeps shutting off when Im at a red light. I took it to a mechanic and he told me I needed to get an air filter, rotor, spark plugs and distributor cap because it kept accelerating and wanting to cut off when Im also at stops or red lights. My obvious question is what's wrong with it. The mechanic didn't give me an answer he just said that I needed all of that. I need to know if it is my engine that is getting messed up and what I can do???