It's more likely that the high Idle is causing the transmission to malfunction. I'd clean the throttle body real good and have the TPS tested. I don't even understand what you said about the transmission. Could hear the sprags? Do yourself a favor and drop the pan off of it. If the pan is full of junk the transmission is wasted. If the Transmission is clean replace the required
solenoid(s).
Might want to try
http://www.bulkpart.com and see if they have the solenoids a little cheaper. The most common solenoid to fail it the EPC solenoid. It is located in the case and the linkage has to be partially disassembled to get it out if I recall correctly.
EPC stands for Electronic Pressure Control. It will cause the line pressure of the entire unit to be screwed up. The only thought I have on you being able to hear the sprags is That you probably have the mechanical diode. It will make a clicking sound when you turn the shaft in reverse. That is normal.
Alan