I have a 2008 Express and for the last 2 yrs I have been having problems with the #8 coil going bad. Everyone just says keep replacing. I have used different brands of coils and they last maybe a month then I get rough idle again. Took to a mechanic and they have replaced 3 times and still having problems. Any help would be appreciated. Thanks Jeff

 

Find a mechanic who will look for the cause of coil breaking down, such as higher than normal resistance in wires/plugs or trigger signal from ECM not normal.

Best to find someone who can analysis problem looking at ignition wave patterns on a scope.