I can't ID it, either...but I'll offer some (FWIW) thoughts:

I think it's most likely Italian, most likely some sort of Columbus tubing, and (tell us the rear spacing) most likely from the early '90s...based on the Cinelli spoiler BB shell, that style of forkcrown, the "shot-in" fastback rear stay treatment, and the FD bracket and dual WB bosses...but that's all just guessing based on generalities.

I'd further guess that, since there's not much else to hang a name on, the best clue to pursue might be the Columbus branded DOs and fork ends. They are not all that wide-spread in use and you might just find a match by comparing to other brands that used them.

I just might start a thread to gather pics of brands that used them...might be helpful to you and others, too.