Peugeot 307 intermittant starting problem

Car has recently developed an intermittent problem when starting. When car has been left for a long period of time, be this overnight or when parked and then started after a day at work. Sometimes when I go to start the car, it sounds as if it is misfiring, the car judders violently and the rattling/knocking from under the car is quite worrying. Sometimes the car will then stall or sometimes the problem will clear and the car will behave as it should. If the car has stalled, when restarted for a second time it will start 99% of the time without the problem reoccurring. The car drives as normal, no hint of judder, misfire, idling or any form of problem. When the car does stall, there are no other warning lights on the dashboard or centre console other than you would expect to have. I have had the car put on a diagnostic laptop and no warnings or problems have been highlighted. The problem has also not occurred whilst it has been at the garage. Any ideas?