Low volts at idle

So I have been reading up on many post so to save confusing myself I figured I'd start a new thread. My problem is that my volts drop to about 12 when I'm in drive at idle but instantly jump when I give it gas. With my headlights on the volts drop to 9-10 and my electric gauges start bouncing. I'm gonna be doing the relays for my headlights that I've seen in other posts but that won't help the low volts during the day. Does anyone know the fix for this? I was going to buy the powermaster alternator but apparently that won't help at idle. Thanks for any input! -kory oh and I have already checked and replaced my alternator and regulator and replaced the wires that go to the alternator but with no change