You have a direct vent fireplace. The flaps are pressure relief flaps. They should cover the hole they sit on. These flaps have nothing to do with the flame dying out. What you describe is caused by lack of combustion air into the fire chamber. This lack of combustion air is causing the fire to starve and go out. Pretty much the only thing that can cause this air starvation is a restriction in the combustion air intake in the flue system.

Who did the installtion? What model is it? Where are you (city) located? Is it vented straight out the back,through the roof or other.
If a new home, go to your builder first. They will contact the fireplace subcontractor. The builder will have more "juice" than you will in getting it corrected.

Until then don't use the fireplace.

Thanks for the info. However, when a repair person come to our place, he put insulating rope under those flaps where there was none before. Now the fireplace works fine. I don't understand this since the fireplace has worked for eight years prior to this without the rope.

I found out that my fireplace is doing the samething, it worked all through construction and a year of being in the new house. Now if I start the fireplace it will run I see the flame start to flutter then I shut it off. By doing this 2 or 3 times the fire is normal and it runs till I shut it off. My question, is the flue to cold and needs time to vent properly or is there a combustion problem?