My dc5 has a problem on cold start in that it sounds like it's misfiring for about 5 seconds with the revs bouncing from 500rpm upto 2000rpm and then it settles back to a normal idle. This problem only occurs after the car has been driven hard the day before, when it's not driven hard it idles fine from cold. This is the only time it misfires/sounds rough the rest of the time it is fine. Does anybody have any ideas? Thanks.