One of my engines, an Atlas GP40-2, recently developed an interesting problem. When I apply power in DCC, the engine will move; however, after a few seconds (up to about 10), it will then stop. Usually it will resume moving if I adjust the throttle again, although sometimes it takes a second. The lights always remain on if activated. Sometimes I can keep it moving with constant throttle adjustments, but it will still try to slow down on occasion. I've had this engine for a while now; probably at least eight years. For most of that time, and still now, it has been equipped with a personally installed TCS AMD4 decoder. This problem only came up a couple months ago, and since I've been building a layout I haven't touched it in most of that time. The problem also seems to be happening in DC mode. My DCC system is a Digitrax Zephyr Xtra. Does anyone have any ideas what might be the problem or solution?