Re: Got an 06 commander this summer
Welcome to the garage.
The P0750 means that there is a problem with the low/reverse solenoid or circuit. Does it shift different? The commander uses the 5-45RFE on the 4.7? If so, i would start checking and cleaning the large connector on the left side of the transmission. Moisture or dirt can give strange behaviour.
If it doesn´t help, you most probably will need a new TRS/solenoid assy, which sits on top of the valve body. The transmission pan needs to be dropped for this.
If it comes sofar, i could give you some directions on how to do this.