I don't know a lot about the Steam version of the game, just what I pick up reading posts on here, but isn't it possible for you to get Steam to verify the vanilla game files? I agree that you have something not right, and it does seems likely that it's vanilla Oblivion (you gained a bunch more of those Bound item warnings).
Perhaps a test using a new game start rather than loading a save will help narrow it down (I'm thinking that all those Bound item errors are just a result of whatever the underlying problem is, not necessarily part of the problem). A crash log from a new game start will not have any "baggage" coming from the save file (and if it doesn't crash may point towards save corruption being the problem).
Alright, I'll try that. Will edit the comment once I get the info.
Edit: Created a new game and proceeded to do the main questline. When I tried going to Kvatch, the game froze https://pastebin.com/WDdgdrAn
Providing your load order hasn't changed since you posted the load order Paste Bin, your warnings from Paste Bin lines 4 thru 289 are all Better Cities related (specifically Better Imperial City FPS Patch.esp). The two Oblivion Uncut warnings are consistent across all of your Paste Bin crash log postings (just changing position in the log). You have a new one this time I believe at Paste Bin line 296 that according to the mod index number (24) should be related to DLCFrostcrag - Unofficial Patch.esp (though an error from before that is worded exactly the same seemed to reference Knights.esp ... could be a load order change at work here). The four Offset Collection for Worldspace warnings remain for the same things.
I would think that the final Crash Log entries are the ones most closely related to your crash, but the final two give no clue of their source, and the one at Paste Bin line 341 introduces a new one that doesn't make sense since the mod at index 2F is ShinySeptims_Septimus.esp (what would it have to do with ChorrolStoneWallStone01 ... makes no sense except maybe a dirty edit, or again your load order is different from the last one you posted).
My own tried and true method for installing mod is simple ... install one mod and test thoroughly. Once satisfied that it is working correctly add one mod mod (and of course test thoroughly). Yes it takes some time (I spent well over two weeks setting up my current load order, but a lot of that time was spent getting Basic Primary Needs, Basic Physical Activities and Realistic Fatigue set up the way I wanted them ... they have quite a bit of overlap and interaction)).
The advantage that my way offers a situation like this is that when you add a single mod to a perfectly working game and then something breaks it's a trivial matter to figure out where to start your troubleshooting. As you can see, your situation right now is more akin to trying to find the one end of a piece of spaghetti you need to fix ... on a whole plate of spaghetti.
Edited by Striker879, 30 August 2020 - 09:44 PM.