I have a pontiac g6, 2009 with 22,500 miles on it. in the last couple of weeks, the cruise control has shut off while engaged on the highway. shortly after this happens the car with buck several times( the tachomoter will also "bounce" for lack of a better word) and then calm down. The cruise control will not re-engage after that and may take up to 15 minutes before working again... once was after being on the highway for approx. 15 minutes once on a road trip for about 1 hour. There has been no service lights or warnings on the information center... Any ideas? It is still under warranty and would like to have an idea of what it may be when i go in so that it can be taken care of.