Car Cuts off at stop signs or Lights

I drive about 60 miles a day, mostly on the freeway. For the past month or so, at least 2 to 3 times a week, when I start the car up, it will idle low and when i put it in gear, it will shut off. I have to start it in neutral, with one foot on the gas pedal and the other on the brake to raise the RPMs, put it in drive and take off..... then when coming to a stop, put it in neutral and repeat the process... Whats my problem??? Cause it dosent happen all the time.