Have you had your ABS serviced in the recall?

From what it sounds like is that you had 2 tires with good traction and 2 tires with bad traction.

Although I am not sure if it applies to your year, this is a known problem with the Isuzu ABS system and according to isuzu it can cause extremely longer stop times and even lead to collisions.

Goto your local Isuzu dealership and see if it has been fixed and if not have it fixed immediately.

By the way, when correctly setup, ABS does greatly reduce stopping times because you have maximum stopping power during slight slip of traction as with ABS, but without ABS if the wheels lockup the stopping distance is increased greatly.