Help

Now, Im generally pretty mechanicly inclined, but I am having a problem with two of my vehicles that I cant figure out at all. My second problem is that my 92 eclipse will start if I jump it, run for between 3 and 10 minutes and then shut off. I just replaced the alternator in this vehicle as well and so I know that that is good, but I have no idea about what is wrong now. Im open to any suggestions for the vehicle.:banghead: