I was recently removing old wires from the firewall and found the power wire from the back of the altenator to the battery post on the starter is not hooked up. I notice when I start the car the headlights and instrument panel would be bright and then dim down. Only when I press down on the gas pedal everything would brighten back up until i come to a complete stop.

that means the alernator is not charging the battery. reconnect it and you should have no probs