So, I bought the Oblivion GOTY Deluxe version on Steam a while back, but frequently I would get many crashes from having too many plugins. (The amount of plugins+BSA's limit- around 400.) Is it possible to remove some of the DLC's from the folder? At the moment all I want is Mehrunes Razor, KOTN and Frostcrag.

I only ever had Oblivion's disc version, but does Steam not give you the auto play prompt that allows for mod activation/deactivation? If not, it is pretty easy to move the .esp files if you have access to the folder. If you can't choose which to deactivate, though, that may cause the game to get a little confused on loading a save.

It's not so much deactivation as it is removing them from the Data Folder. Apparantely when the amount of esms/esps/BSAs/ approaches a certain amount, the game begins to crash a lot more.

Wrye Bash solves this problem through ghosting and Shademe's mod Trifle also solves this problem.