Speed Control Springs problems of the 2006 Chrysler Town & Country

It was a clear day and the pavement was dry. I was driving about 55 mph on a 2 lane highway heading west on dayton-yellow springs rd near fairborn ohio. The car appeared to speedup on it's own, I hit the brakes and let up to try and gain control. The Mini van went left of center, spun back to the right and flip on it's side into a ditch. I had been complaining to my husband that something was wrong with the van. He drove it a couple of times because of the high mileage had new tires put on. A couple of days prior to the accident, a CO-work drove the van and she said something did not feel right with it. She has drive my van numerous times in the past.