First, check if you don't have another AFCAD in conflict, by using the FSX Airport Scanner program.
Also, as you can see, JFK is supplied with TWO approach files (look under the fsdreamteam\KJFK\scenery folder ), one for the Canarsie approach and one for the ILS, the Canarsie one is installed by default, but this can be tricky to fly for AIs, depending on their flight model ( some of them can do it ), so you can try switching to the ILS file, and see if it works better.