I'd have a look at the fuel consumption and make sure the value in fuel_cons.ini makes sense. That's how AI behaves if there are issues there. May also want to look at the damage sections, but I'd try fuel consumption first.
Usually fuel is the problem 'cause I already had this "bug" in other mods but here I don't see cars pitting in the whole races I tried...
True that I don't used fuel_cons estimation for it so maybe with some particular combination it behaves like this.
Try putting in data folder a file named "fuel_cons.ini" and write into it these lines:
[FUEL_EVAL]
KM_PER_LITER=1.6
If that solves, ok, otherwise I will have to thisnk to something different