Pulled the gaskets. They aren’t stocked locally, so I did my best to peel off the thin paper gasket without messing up the thicker lower gasket. Also replaced the lower adapter gasket that I bought but never installed. No immediate change.
My next move is to obtain a timing light (borrow or buy used for cheap, since I have one already that’s lost at my parents’ house). Perhaps timing adjustments by the ECU are putting me in and out of time due to the base timing being off. Otherwise, barring some unexpected carb issue (odd, I just rebuilt it), my only other thought is bad gas, but that’s grasping at straws.
Ideas are welcome… these aren’t my forte… yet. I bought the truck partially to learn old systems, and learn I will.