OK. Took the Xfire into my local Chrysler dealer with the intention of leaving it there over night so they could listen to the tappets first thing in the morning. Courtsey car was booked for me to use. I was just about to leave when the service manager said, why don't we start up one of the Crossfire's that we have in stock to see if it's got the same problem, if its the same there's no point in leave yours with us. Outside was an 2007 coupe with 3K on the clock and had been standing for 2 days. Flicked the key and good news, it was just the same as mine.

Jon