Hi Paul,

.......(geography is all wrong)........ The joys of being a mobile tuner! Know how it feels especially when you are dealing with an intermittant fault and car runs fine when you test it. Assuming everything tested OK, I would go for 02 sensor (180,000 miles) and then maybe AFM if nothing else manifests itself. The trick is to get the customer to understand that it could be an expensive fix if nothing else appears, or to wait until the symptons get worse.

Regards

Pete M