2004 F150 5.4L, 240k. Got the truck for a steal and working through a few issues. One that I'm stumped on...windshield wipers.

Condition: Wipers work only on low intermittent and high.
Steps taken so far: Replaced the wiper control arm on steering column with a brand new unit. Replaced wiper motor with salvage.
Results: No change to issue.

Here is a visual of what is happening:

HIGH - Works Normal
LOW Constant - 20 sec delay before swiping
4th level intermittent - Nothing
3rd level intermittent - Nothing
2nd level intermittent - Nothing
Lowest level intermittent - 20 sec delay (Normal)

Thoughts?