After a few months ago i change all my coils and spark plug. After that i notice a reduction in MPG. I was only getting 17.6mpg the spark plug was not gap at that time so after reading on this forum i decided to install new ones and gap them to 0.032 (ngk). right after i start driving and at the stop light the car start shaking a bit and the rpm jump up when that happen but it happen randomly with no mil. i ran a vag-com and no cylinder is misfire. this is a A6 2002 2.7 with 154000 miles on it.