P0741 and No Reverse
 

My V6 RWD 2004 4runner with 180xxx miles on it has been not wanting to reverse. I'll put the shifter into reverse, apply the gas, and the RPMs will go up, but the car won't move. It will do this 90% of the time. The other 10% of the time, it will struggle to reverse but will slowly start moving.
My first course of action was to replace the tranny fluid; it was very dark. I figured it has probably never been changed. After changing the fluid, I went on a test drive, and the code "P0741: Torque Converter Clutch Circuit Performance/Stuck off" came on. The reverse still didn't work either.

I have managed to find almost nothing on my problem. What little I have found is the code could be the result of a faulty solenoid. I just don't know what one. I have no idea if the problem is related to the reverse.

I am completely lost. I can't find any information, and I can't find a reliable source for a solenoid for my exact transmission (a340e). Id prefer not to take it to a transmission shop but that seems to be the way I'm headed because I can't find anything.

If anyone could help me or point me in the right direction that would be much appreciated.