I have an 1987 325 sedan with the 3.4L inline 6 engine that wont stay running, before i got it it sat in a field for a few years so its not in the greatest shape, it'll fire up, run for 4 seconds then die, and i can do that all day and it wont change, I've replaced the fuel filter and the fuel pump relay but that didn't help at all. From what i can tell everything is intact. Any ideas????