I replaced my battery and alternator and my eclipse wont hold a charge for more than a couple hours.

My eclipse one day just died and i thought it was the battery. So i replaced
it. when that didn't help the issue i replaced the alternator. that as well did
not help. ill jump the car it'll catch a charge but when i disconnect it it's a
50/50 chance if it'll keep running or just die seconds later. if i maintain
running it by stepping on the gas pedal and driving it for a hour or so it'll
stay charged for about 6 to 8 hours and just die again. but as i start to drive
right after it's been jumped. it looks like the power is slightly surging from
the radio barely working or the lights inside and out flickering and if i try to
run the ac or heater it kills the car right away. i need help please .