Did the acceleration tsb to my wifes 07 caliber made a huge difference. Feels better. Looks like gas milage is better too. Before we did tsb she was also having a stutter upon further diag it's only while a/c is on. Every single maintenance / service has been done. I've looked it over I see nothing. Scan for codes nothing. Anyone heard of anything similar whether it's a tsb or not. Any help would be greatly appreciated.