1993 Buick Regal question pleaseeessss help!!!!!!!!!!!!

Hi I have a problem it is, he buys a Buick Regal next 93 limit automatic transmission, and go all right but when I arrive between 45 and 65 miles per hour begins to make a vibration of the steering column, but if accelerate a little bit is going to accelerate or slow down and then if that happens sometimes, the owner told me that this is a problem with the chip's car is this true? I'm afraid that is something serious to trasmicion, in fact, not bothering to handle because when one goes faster, thank you very much. if I can help