5300 mobile modem not reading correct GPS data

Odd.  

Falcon boots to 96008N1, what are you telling it to use for your mobile paramters?  Serial NMEA?  9600 or 4800?

I am assuming that since you were seeing the correct lat/long at the previous location that your port speeds are correct from console.  More than likely 9600 8N1.  

I would double check your configs.  Specifically what the GPS feeds the iDirect unit on console, as well as the Mobile parameters that you have configured for the iDirect unit (iBuilder Options file).  Some GPS devices have a config tool that you can use to select what NMEA strings you want to feed it, as well as what port settings you desire to use. I have found that the IDU's like 4800 8N1 better than they do 9600.  Even though that will change the port speed from the norm (read: when falcon boots it sets console to 96008N1).  

Double check everything, if you have a config tool for your GPS, you may want to consider using it.  If anything to double check things and select the strings that you want the iDirect to see on console (there are a lot of them). You may want to consider using 48008N1 and use the serial NMEA setting (either socket or ttyS0).  Experiment with both.