Just found this post by searching up my problem. I think patch 6 completly has messed up a modded playthough. I have the same problem where most areas in act 3 i will crash anywhere from 1-10 minutes. I found that all the major bosses bar Gortash in the area i was able to complete with no issues but anywhere within Rivington, Wryms Crossing and Lower city just causes crashes. I have tried uninstalling all the mods aswell as the standard solutions people say but i still get crashes so very strange. I did load up my first playthough that i played vanilla and i had no problems in act 3 bar the usual FPS drops. Sadly just think youre gonna have to skip alot of the Act 3 content on this playthrough like i have