trany problems

I own a 93 olds 88 and about two months ago it started knocking.. it would come from the transmission and felt like inside the bell housing however about a month ago at a stop at a green light i nailed the accelerator the transimission made a large clunk noise the wheels slipped and pulled into a parklot where i ate. After that i was unable to accelerate fast nor was i able o go past 30mph. I belive my torque converter is bad or lose can anyone confirm this? also i was wondering if both problems are related thank you. The knocking occured even when the engine was not running and in Neutral.