Jumping and bucking upon acceleration?

I have the truck listed above 1500. It starts fine, idle, fine shift into first gear, fine, when you shift into second and accelerate it wants to jump, buck, and the battery gauge goes all the way down and comes back up like I lose all power. Then it’s ok till I try to take off again and I have changed all most every thing I could, and it is still doing it. I need guidance badly.