Well, I'd have to take a Brita filter, a lifetime supply of water purification tablets and MREs, a rebreather, and a hazmat suit.
They might think I was god. Or a demon, probably demon, then kill me. Assuming they didn't, if any of those failed, I would die anyway.
I'd also need period money and an ability to learn the language; and a skill set or something to trade for local period currency.
That, and I don't know how to make a car or computer from scratch. I'd have to "invent" tons of mining and refining techniques to simply have the materials, let alone other processes to "invent" the tools required to actually make the damned things.
Besides, I don't subscribe to a temporal multiverse model of time-travel. Any time travel to what we call our "past" has already happened. If any of us, in the future, go back in time to change something; kill Hitler, save Kennedy, invent cars; we already have, and we failed. If time-travel is ever possible, the world we live in now is the result of all time travel to the past.
Harry Potter, Premonition, and Deja vu (almost), have it. Harry was saved from the dementors by Harry. In Deja Vu, Denzel Washington is going through a bathroom with blood in the sink. After he time travels, he bleeds into that same sink. He sends a message back to himself that is actually picked up by his partner who was already killed because he followed the message. Of course, they throw it all out the window so he can save the day, but until then it worked.
In the future, no one successfully goes back in time and kills Hitler. Not because they didn't try or because some magical cosmic force stopped them, it is because whatever they did in our past already happened in our past. The easy answer is that time-travel simply isn't possible, but even if it is, whatever you end up doing in the past has already been done.
It's a simple concept of time-travel that is hard to explain in a world where time-travel has been depicted by doctors in bowties and teenagers who inexplicably hang out with crazy old men who live in their garage.