hi iv just got a 2wd saff and its just started to missfire and seems to be running rich a friend told me to disconnect the amal valve to lower the boost but hasnt cured the fault ideas please

 

all so forgot to say the amal valve is clicking ??

 

The best and most cost effective solution in this case wouod be to go to a rolling road, but I would change the CTS if over 3 years or so old anyway, as this is so cheap and important, and they do go out reading wise.
tabetha