When I am in 6th gear and rpms are about 3400 and I let off the gas and let it decells to 2500 rms with it still in 6th gear right at 2900-2700 the car vibrates. Its is very noticable to passengers but it is just from 2900-2700 any other rpm and it is fine but as soon as i let off the gas and as the rpms are falling it shakes for the two hunderd rpms. It is more noticable in the shifter and the wheel Any ideas??