'08 S80, Codes, interpret & repair?
 

My S80 has gone into a protection mode (w/engine light) upon start up 3-4 times in the last few months. It goes only 2-3 mph. If i turn it off and restart it goes away and operates normally.
The local shop pulled the following codes:
* ECM-P211800 (throttle actuator control motor current range/performance) * TCM-P074468 (torque converter clutch solenoid circuit intermittent - algorithm based failures).

They downloaded the latest software and felt that would likely solve the problem, but it did not. They said if it happened again, they felt it was likely the "torque converter clutch solenoid".

Any help? opinions? confirmation of assessment? how to replace this item?

Thank you v much in advance for your help!