2003 Ford Taurus Car dying

I am having problems with my Taurus dying whild idleing or when driving down the street. When it dies whils drivingmst of the time it starts itself back up without using the key. When it dies while idling it starts with the mph guage jumping up as high as 20 mph. Then it will die and when it does this sometimes it will cause the radio to completely reset lioke the power from the batery was disconnected. I have had it at ford. The first time they said it was a power problem and replaced the alternator, ac compressor. The next time they replaced the starter. It worked for a couple of monthe and now it is back and worse. It doesn't do it always some times it will go for a week and work fine. Now there are sometimes when I get in it and the power is off, you can hear what sounds like a relay continually tripping, with a clicking name. Please help if you can.