Wondering if anyone has any similar issues. Our 2011 Buick Regal "chugs" at stop lights, has trouble starting, will stall-out after starting and will turn completely off while driving down the road! All at random. It has been to the dealer 4 times (2 different dealers). And is usual; all they say is we can't find anything because there is not a service light on. Really frustrated with GM. Not sure what to do.