Hi Mark,

My initial approach would be to ensure that the throttle body/plate is clean. There appears to be no ISCV or similar to clean. I would want to see what the emissions are like cold (hold throttle open slightly) and hot. I am assuming the temp readings you have given is the air temp sensor. I would like to see what the CTS is doing from cold. I suspect that the replacement throttle body might require adaptions reset if all else fails, although I have on occasion managed to get the ECU to re-learn the new parameters by driving the vehicle for 20 mins or so.

Regards

Pete M