Shannan,
It still looks to me like too much insulin, but I know it's hard to "get that" when you are seeing black numbers. When you shoot a dose of 2u, many times even that looks like too much. If he's dropping 300-400 points, it's "too low" for him (even though the numbers are still above normal), and his body seems to be reacting to the drop by bouncing back up to higher and higher numbers.
I'm still thinking that 2.0 or 1.75 would be better. They may not give you yellows and greens, but I do think that you would see fewer reds or blacks at a lower dose.
Carl