my car tends to shake only when i stop at signs or lights.

Is there a Check Engine/ Service Engine Soon light on? If so a scan tool will b needed to retrieve codes stored in the computer of your car. A vacuum leak or ignition misfire, or a failed idle control issue could cause the shaking at idle if it is engine related. Engine mounts are there to isolate engine vibration from the chassis so the ride is smoother for the passengers in the car.