stalls and cuts out when trying to take off

I had taken my car back to dealership witching the first 2 months thinking there was something wrong with it. Being as it has turbo it's meant to get up and go but not this car so much it has always stalled not everytime but more then I want it to. It's always acting like its cutting out like its not getting enough gas to it. I took it over when I first got it and they said it was just the turbo and that is what they still say is the problem. I've had several people ask me why my car sound like a truck when it starts and when you try to get on it. It stays revved up high and is sometimes hard to get into gear because of it. It shifts very hard and rpm are very high when it finally shifts. Turbo makes a whistle noise constantly. It's caused me to almost have an accident a few times because ill think I can pull out in front of a car and if it wouldn't stall out I wouldn't have any clearing issues but it stalls and it comes really scary not knowing if it's gonna get stall out or if it's just gonna go cause it doesn't do it all the time.