New fuel filter on = super easy, the old one was definitely dirty. Let it idle for a bit to see if any air got in to the carb & apparently if it did it escaped out since no stalling, sputters, etc ~ yay, no problem.

Used that new tester mentioned above and it showed no problem with the battery (no power was lost overnight while it sat off). Tester also showed no problem with the alternator. Hmm.

Did notice a small chunk out of the outside of the alternator belt - weird, and thought maybe it was a little loose, so went to the parts store (thank god for neighbors) and got a new belt & put on no problem.

Taking the truck for a test drive now & will re-check the battery/alternator with the tester later on today.

MAYBE with freeway driving the belt was getting warmed up enough and was just loose enough to cause a charging problem... seems weird but maybe... will update as soon as the next symptom shows.