After a LOT of different opinions and work, going on months now, after having the head pulled twice and all sorts of excitement, the car now runs (sort of). I took it back finally and decided to check into it myself.
The injectors on cylinders 1 and 3 are wide open. 2 and 4 seem to be cycling normally. If I disconnect 1 and 3, the engine runs just as you'd expect with two dead cylinders. When they're reconnected, it runs very rough, and I suppose that's why they were convinced it was a timing problem intially. Swapping the injectors around makes no difference, it's not a mechanical problem with them, and from what I could trace by sight, it looks like there're two wire pairs, but for
1-2 and 3-4, so why one of each pair?
This thing's been through dealership mechanics and another shop, both of which pulled the head, so it's very possible that something's either not connected or not connected properly, or the entire problem was with a module. I just don't want to deal with any of these "professionals" now if I can help it.