torque converter not staying engaged?

[driftphenom]

have an auto 95 s14. runs, drives fine when o/d is off. but when i put it in o/d, it shifts to fourth, then when the torque converter kicks in, it keeps jumping in and out i think. or engaging and disengaging. it feels like the car is studdering. but it only does it while trying to mantain a speed. not while accelerating. it also doesnt do it at speeds below 45 or so mph. i read the fsm and the diagnosis instructs me to pull the oil pan, which im not a fan of. was just looking for advice or someone that had the same problem. im hoping to do a 5 speed swap eventually so i dont really want to pull a tranny if i dont need to. is this torque converter a gear or shaft or what? just need to know if this is chewin up the gears or just a solonoid or what. thx in advance.

p.s. i googled how an auto tranny works but it made my brain hurt to try to comprehend. i need lamen terms