I wanted to make an update and see if you guys have any ideas. I've isolated the misfire to Cyl 4. I swapped the plug to Cyl 2 and the wire to Cyl 6, no change. I replaced the crank sensor, no change. I've done a few crank relearns, no change. I've replaced the cap and rotor (which were pretty crusty), no change. I haven't touched anything fuel-related yet. I've hosed down the intake with starting fluid with no observed rpm change (i.e. no vacuum leaks).
Now, I've observed that the misfire is occurring at light throttle (between 35 - 65 kPA), but NOT at idle. If I get on it, there's no logged misfires. If I have it in neutral and hold the rpms over 3000 rpm, there's no logged misfires. When I am in that band of 35-65 kPA, cruising along, it logs a lot of misfires.
This morning, over a 50 min commute, it logged 29,635 misfires on Cyl 4. If I average 2000 rpm (just a guess), it ends up being 60% of the ignition events were misfires. Here's the thing, I can't tell that it's misfiring. If the SES never went off, I wouldn't even be looking at this.
The truck did sit for a few months while I changed out the rear axle, so maybe the injector is gummed up?
So what does the hivemind think? Do I pull the injectors and clean them (there is a place near me), or do I just ignore it at this point?