help with rattling noise. sometimes wont start.

[808faded]

i have a 91 coupe sohc. couple days ago the car has been making a rattling noise coming from the engine. at first it was sort of quiet but now its really loud. the noise starts when i turn my car on and normally it would stop right after but now i just always hear it. i looked under the hood and the noise sounds like its coming from the engine but idk. sometimes when i start my car it idles for about 2 sec. then dies. anyone know what could be the problem?