I'll bet on the air in the steering, that has come up twice here this week. My 99 truck had a steering shudder(by the alignment shop) on its test drive. I had everything dry, new pump, lines and cleaned reservoir. It gave me no trouble, but the alignment tech was surprised on his short test drive.
It seems like a more common issue than normal vehicles. It never did any of that for me, the tech worked out the air.
Section, drive it more, cycle the steering while running quite a bit. Surely it's not a hard part that has been missed. Night,