sounds like you need a new alternator or have a grounding issue somewhere
check the radiator
The battery ,which gives power to the truck, looses its power because the lights use power from the battery to work. It's just like a batery for a toy.
I have a 1999 dodge neon that looses power and can't get to cruising speed
Lights must be on during periods of restricted visibility. ref: EQ-2
It requires more power, RPM goes down when demand for power is higher especially if lights are on or air conditioning
In the USA, congress looses power never!
i cannot fine which relay has turned off my fuel pump and i do not have power to my lights
Retained Accessory Power. When the Ignition is turned off, power will stay on for a short period of time for things like the radio, and interior lights.
A magnet looses its power when heated.
dodge Dakota 1993 looses power pulling trailer up hills, whats wrong?
When key is on, is there power?(lights on the dash) If so, check starter/relay/solenoid. If not, check battery terminals, cables and fuses.
Not unless there is some sort of power drain...little lights, or clocks, or anything needing a continuous power supply to maintain integrity.