truck keeps dieing

[1988ranger_ky]

i have a 88' ranger ford, I can start it up, then after about 15 minutes the lights start to dim out and the truck turns completely off. The engine runs great and idols good, 2.9 engine.... need some help

 

[The purple one]

Do you need to charge the Bat.? Could be a bad Alt. or a lose Alt. wire.

 

[1988ranger_ky]

i have a new bat and alt it start up fine run great but when i drive it . it will go for a bout a mile the it will lose all power im thinkin it mite be fuel filter but i dont know