cold69bird

i recently purchased an 01 t/a with several mods including and yank 3500 convertor,the problem i am having is about once every two or three days it will turn on the service engine soon light and will start to shift very hard.i found the code was a p1870 code(trans component slipping) and the trans is not slipping at all,so my question is,will this happen due to the convertor slip or is there a way to change the window for slippage in the pcm to avoid this problem. thanks in advance for any info.