Ok sometimes when i start my car the car will get a higher idle and shake then when i put it in drive and drive off the car will make a loud helicopter misfire sound and it will only do it when the car is first fired up and if i sit in park and shake the steering wheel the problem will stop SOMETIMES. What is it? the car seems to lose alot of power when it does this but im to scared to floor it cuz it gets really bad. all suggestions welcomed.... thanks.