What did you do to get it to pick up a signal at all?
I've done the 8322 NV edit and tried both GSM/WCDMA and Global modes by going into *#*#4636#*#*. Phone is stuck on "Searching for Service". Even tried a few build.prop edits and using build.prop from my RAZR M. No luck there either. I've tried flashing XT907 modem, also erased modemst1 and modemst2. I also tried with and without flashing XT907's fsg. I don't know what fsg is, but the FXZ always flashes modem, fsg, then erases modemst1 and modemst2. No luck there either. Can't even turn on the radio with the modem FW from XT907.
The fact you managed to get it to show a signal bar at all is further than I got.