Over the past week my truck has been bogged down when trying to start it, but not all the time. Starts up fine for a couple of days and then this AM, almost like the batteries were dead. This PM, started fine, no issues. Doesn’t matter how long it sits, hours or days it’s just been random. Batteries are both fine, tested. What could be a possible problem? Starter going out? Stationed on Guam, so trying to look for a little insight before I take it to a diesel mechanic here. TIA.