Hello. When the MKS is in 5th/overdrive and cruising at a steady speed if I slightly depress the accelerator there is a slip/jerking motion when it downshifts and comes out of overdrive. It also does this when slightly accelerating from cruising speed without it shifting down. Could a transmission flush possibly fix this or am I looking at a more serious mechanical issue? The car has 90k miles on it and have not flushed the ATF fluid yet.