1997 Ford Taurus Poltergeist Radio

1997 Ford Taurus 6 cyl 57,500 miles

So I recently purchased a 1997 Ford Taurus with 57,000 miles on it. It was originally a company car but when the company went out of business the car sat in a garage somewhere for a long time. Anyways about two weeks ago I noticed that the audio would cut out every time I put the car in reverse. More recently it's been doing the same in drive. But every time I put on the brakes or put the car in park or neutral the audio comes back in. It doesn't make any sense to me. It's not a loose wire and the fuses aren't blown. I took it down to autozone and all the morons there told me that they have no idea what it is and that my car must have poltergeist or that it may be a ground. My friend's dad said he thinks that it's my Neutral Safety Switch or something like that. I could really use a professional opinion though, but I don't have the money to waste on a mechanic that will just fool around or try to pull a fast one on me because I'm a girl. HELP!