I am the owner of a 2004 CTS, for the past month my car when in park or when I come to a stop and apply the break has been hesitating as if it will shut down but it never does. When I apply sudden pressure to the gas it hesitates, the check engine light flashes and there is a delay in the acceleration. It also does this going up hill especially. Any ideas of what this might be would be greatly appreciated.

Thanks guys...

 

Have a scan run to see what code the car is storing. You will have an idea where to look. Auto zone free - dealer more accurate $????