Little late, but...

This used to air on Adult Swim as I was getting out of high school, and I loved it. They showed it through twice, up to a point where Conan meets some other genius detective boy the age of Jimmy, and that boy gives Conan alcohol and it makes him sick and he turns back into Jimmy.

Jimmy solves the case, but quickly turns back into Conan and is never to be seen from again. At the end Conan was trying to sneak some alcohol from Rachel's dad's shelves but Rachel caught him, and thus was the end of what Adult Swim had, I'm assuming what was translated in America, at that point, and so they restarted. When they got to that episode again they stopped airing it.