OK, now this gets interesting. I tried MAF cleaner. No improvement.
If I disconnect the MAF, the truck runs - not well, but runs. If I connect it, it dies immediately. So it must be the MAF, right?
Replaced the MAF. Starts and dies. Unplugged the new MAF. Truck starts and runs but somewhat poorly. No codes unless the MAF is disconnected and it is a MAF fault - of course.
Any Ford geniuses out there?