I have a 1999 Grand Prix with a 3.8l Supercharged. Today I was driving and the service engine soon light came on and it was blinking. I have had it come on before but it was not blinking. It drove very well at higher speers ( I was on the expressway, so 65-75 mhp) but in stop and go traffic it was chugging. It as not making any weird noises or anything, but it just seemed like it was heistating a little. Also when I tryed to go from lower speeds to higher speeds, the supercharger was making a rattly sound. Keep in mind this is a new supercharger that I replaced about a year ago, so i dont think that the superchager is the issue. Any advise?