When i first start my jeep in the morning the voltage is fine and reads at a little over 14 volts. But when the engine gets up to temperature and some time driving the volts drop down to 13.4 volts. And when i shut it off and come back later to restart it, the voltage goes up to 13.4 and then quickly down, then comes back up to 13.4. I just replaced the battery, alternator, untightend the grounds and retightend them. I don't know if my alternator wire harness (field circuit) is going bad or if something is grounding out on the engine when it gets hot or what. Any ideas or suggestions?????