Why makes a 1989 Chevy truck start idle rough and automatically dies out?

It could be a number of things. Generally, it is the fault of the fuel pressure regulator. Also, the excess dumping of fuel may have contributed to a bad 02 sensor. Or it could have something to do with the distribitor cap and rotor or the spark plugs and wires. Or it could be way out of timing. Or you could have a air filter that is just that plugged. Or the carborator is plugged. Like i said it could be any number of things, all you can do is play around with it.