Thottle problem!!?

I have a 2005 Renault Traffic with 195000 k and the car starts and runs ok but when I stop it for about 5 minutes and try to start it, it starts but when I step on the thottle nothing. I have to stop and start the car 2 too 7 times before the thottle works. If I let the car sit for 20 minutes or longer then it starts right away with and the thottle works fine. Can anyone help?????? Thanks!!!!