1996 Mitsubishi Eclipse Stalling sometimes when cold

I have a stalling problem with the car sometimes when it's cold, now this dosen't happen all the time maybe twice a week. When this happens, the car will start and ideal but when you give it gas and let off the gas it will stall. The car will do this until it runs for about 30 minutes and then it runs fine. Other then that the car runs like new. A friend told me to change the fuel filter, I did so and it's still doing it.