An update: After quite awhile, it did finally throw a code. P0300. Not too helpful, but did give some direction. I started with the easiest. Replaced plugs with AC Delco iridiums, and put a new wire set on. I have learned not to start this job on one of these trucks without a new set of wires on hand lol. Anyways, by golly, that solved all of the problems. it runs smooth now. It has not gotten to all sensors ready status yet-- waiting for evap still -- but there are no codes pending.