Even if you got the clothing right and knew a lot of languages, you'd be in trouble. Languages drift. Just try reading English from a few hundred years ago and it's hard to understand.

And if you got the clothing right and knew the language the way it was spoken at the time, there are still barriers. You probably wouldn't have the behaviour right for that time. You wouldn't say the right thing if someone sneezed. You wouldn't give the right courtesies to the right people at the right moment. Basically, unless you were in a huge city you'd always stand out as the foreigner, at best. In a big city, they might be used to foreigners, but you might stand out if you had anything unusual about your body, including basic dental work.

You'd also be the time travelling version of Typhoid Mary. Imagine something like when the Conquistadors stepped into the Americas. Suddenly everybody around you is exposed to the diseases you carry but you're immune to. They might not have disease theory, but they might notice that the people getting sick are the ones who were closest to the outsider.