I generally advocate you eliminate the torque converter in the transmission to diagnose it thoroughly. Present day torque converters have electronic Charge of the clutch operation. The tension in the torque converter clutch is regulated by means of a key regulator valve which can be piloted by a solenoid (see https://torqueconverterclutch74062.blog4youth.com/34883342/fascination-about-torque-converter-clutch