I have the GT V8 (2007) and am experiencing selector problems with the auto box. On the dash the "O/D OFF" lamp is flashing with the "EMISSIONS" lamp (engine block in orange) illuminated. The box is stuck in 4th gear although it will drive like this. When in this mode at a standstill selecting R the chage is very heavy with a jerk motion. After a couple of miles the box shifts into neutral and after pulling over and selecting PARK the box goes back into normal mode until it happens again. Is this the solenoid, selctor switch on the shift handle or other?? Any help much appreciated.