If it runs sometimes and dies sometimes, you can "generally" rule out fuel pump; they're either a works-or-is-fkd kinda part. Could be what is controlling fuel circuit (circuit opening relay, as mentioned before), or, as my theory is, Throttle Position Sensor. My 87 kinda has similar conditions, but it has only happened twice in the 9 years ive driven this truck. Starts, stumbles and dies (like circuit opening relay), or the second time, started and idled, but as SOON as I tapped the gas, boom it died; a dead giveaway that its a trottle-controlled issue (which could be a lot of things, but TPS makes the most sense) so I towed it home, and as soon as I got it home, started, ran and drove fine, and haven't had a problem since. That was two years ago. I'd look into the TPS being the culprit, mind you, internet diagnosis is ALWAYS hard. They're pricey, as hell, but, I am "friends" with a milf who works at the local dealers parts counter, got a name brand replacement (something dealers tell the customers is unavailable to the public, but they can actually get) for I think 70-80 bucks. If you do diagnose that as being the problem, I'm sure I can order one for you and ship it to you. Happy hunting
