Engage

Check the transmission fluid and retrieve the trouble code as a start.
If you get a code post it back in here.
If the transmission fluid is full let me know.

P0705 refers to Park/neutral position switch
P0744 refers tp A/T TCC S/V function (lock-up), This is not caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve operation, malfunctioning oil pump or torque converter clutch, etc.
P0797 refers to Pressure Control Solenoid Valve C Stuck On Graph.
†The pressure control solenoid valve C is normally low, 3-port linear pressure control solenoid.
†The pressure control solenoid valve C is activated to control the apply and release of the second brake and first and reverse brake, and torque converter clutch.
†Lock-up operation, however, is prohibited when A/T fluid temperature is too low.
†When the accelerator pedal is depressed (less than 1/8) in lock-up condition, the engine speed should not change abruptly. If there is a big jump in engine speed, there is no lock-up.

I would have to say mostly because of the code P0744 that says it is not an electrical issue but a mechanical malfunction such as control valve sticking, improper solenoid valve operation, malfunctioning oil pump or torque converter clutch, etc that a rebuild or just a salvage yard transmission.