Ok, got the DB210 and a 20V power supply capable of 8.5 amps. I've got enough power now. I cleaned the track, and tried the Zephyr again. It got a little farther (tracks were very dirty), but still had issues. But I installed the DB210 and now it's working like a champ. I'm going to clean up some of the drops, and solder a few joints around the turnouts like you said @Doug-Sr. It still flickers a bit when it hits them. But I don't have my drops between the turnouts wired either, so that may help as well.
Thanks a lot for the suggestions. I didn't pay enough attention to the boosters from Digitrax as an alternative, so I didn't consider them. But that was a good fix. In hindsight, 3 rail tracks plus a power bus is a LOT of wire to power, and I can see a small solution just not working for anything even a little bigger like mine. Plus, having a newer Lenovo laptop power brick that is 20V made it possible to keep the costs down. The place that just RIF'd me may never even miss it .