Good Afternoon

I was hoping for some direction on a problem I am having. I have an 01 E430 with 59K miles. The car starts right up in the morning with no problems. The problem is after the car sits for 2-4 hours it takes a while to start. This happens only after it has sat for 2-4 hours, not 1 hour, not 8 hours. It's very strange. I took the car to the dealer and of course it didnt happen to them. They performed a scan and found nothing. Any advice on what I should do?