The primary automotive application with the lock-up principle was Packard's Ultramatic transmission, released in 1949, which locked up the converter at cruising speeds, unlocking once the throttle was floored for quick acceleration or as being the car slowed. So, you suspect your torque converter is likely to be acting up. https://andersonrenwb.shoutmyblog.com/33152621/5-simple-statements-about-torque-converter-clutch-explained