maybe, but I am not seeing a particularly good case for slander. It sounds like there is some basis for his allegations, i.e. "2002", however, in order for him to pull people over he must have a reasonable suspicion that the person has been, is, or is about to be engaged in criminal activity. If this is an ongoing harassment you might want to consider a departmental complaint, as a first step to a potential lawsuit against both the officer and the department.
The biggest problems I see in your case are both liability, and damages. That means it is likely not a great case, as those are two of the cornerstones in any case of this type. I would recommend that you keep a record of when the officer makes these stops, what is said, and how you know, in an attempt to help overcome your liability issues. As to damages you are going to have to quantify how you have been harmed in a monetary fashion. In your description it sounds like there are no quantifiable damages yet. A better case from a damages perspective is one where you feel compelled to send the children, and perhaps yourself, to counseling in attempts to deal with the officer's actions.
Good luck, I hope you are able to get the officer to leave you alone.