Nostalrius Begins - Quality wow vanilla realm (1.12)

So I tried out a slam fury spec, but no matter what I do, slam resets my attack timer. I can slam 5 times in a row, and it will still take my 2½ second before my next attack goes off. What the heck is happening?

That's actually intended and not a bug. You need to use slam right after your weapon hits to maximize damage with it.

I assume you're coming from Emerald Dream, where slam was bugged to not reset the swing timer. It's still good here provided you don't need to move, as it reduces a 3.6 second swing down to 1-1.5 seconds, but it's not as great and it's also harder to use properly.