WHAT'S HAPPENING?

I just purchased a 2001 Ford Escort (Pony), 66,000 miles, don't know the engine size. My '95 Honda was not worth putting any more money into it, so I needed a vehicle. Fast. I bought it "as is", no warranty. I had to drive back to Austin from Corpus Christi that day, so the salesman was aware that I had a long trip ahead. He assures me this car will make it. Well, it did, but now it's not acting right. Here's my question. When I slow down, or stop at a light, the sterring wheel, and really the whole dashboard, vibrates like crazy. The car also has a rattling noise at times when I idle. What's happening, and what do I need to do?