Why does my Buick Excelle shake at first?

Hello, check whether there is too much carbon deposit on the throttle, and cooperate with the throttle when cleaning. Check whether the idle valve is too dirty and clean, check whether the air intake system leaks, and then repair and replace it. I hope I can help you. Have a nice trip. If there is something wrong with your car, ask the car mechanic. 4S shop professional technician, 10 minutes to solve.