There was no FPS cap in D2:ED, AFAIK. That was introduced in the original release of DKS, and then the option to change or remove it was added in the second DKS patch (along with a higher 'nightmare' difficulty level, since various changes made the game easier).
Include the Securom key from D2:ED when you contact support, and they can provide you with a voucher to get the Developer's Cut version of the game from the Larian Vault. The Developer's Cut is essentially DKS (a remastered D2:ED with the add-on Flames of Vengeance) with an optional 'Developer Mode' cheat window.
