I have just finished the boogre lair quest '(got the lamp by the way) but i got the feeling tha grunaxe was dead since i found him (or rather what was left of him in the pits*) Am i missing something? Or do i find him somewhere else?

Yes, you missed his ghost. He's down there somewhere. You have a bend in the lower levels that will bring you to the Idol. The other side brings you to the "ghost area"

Good luck