It took me about 100 miles worth of driving for it to stop shuttering. The more miles I put on it the better it got. The new fluid is literally cleaning sludge/deposits/crap whatever you want to call it off of the internal parts of the transmission and depending on how "dirty" your internals are it might take a while. Try throwing the transmission in neutral while decelerating, and if the noise goes away then it probably is the transmission. Pay attention to the RPM to and try to locate at what RPM it is the loudest, also see if it happens more when it is cold or hot, sometimes the noise can be the power steering. First start of the morning when the engine is cold, pop the hood open, start it, and start turning the wheel that will tell you if it's power steering or not. I also have a slight noise in the rear diff I think I've seen other people state this but never heard anything about it blowing up. I change my fluid to some heavy weight AMSOIL diff fluid, and I put on new tires the noise didn't go away. I also don't have any driveability issues so I'm not to worried about it. If your shuttering goes away, my personal recommendation is to drain all the fluid one more time, change the mesh filter, flush the tranny cooler, add the tranmission fluid, then add the shutter fix. This way all the "dirty" fluid used to clean the internals is out of the transmission, the old mesh filter is out, and then the shutter fix can "condition" all the parts with the new fluid. This will make sure the shutter fix isn't coating old/dirty fluid. My background is 30 years automotive, 11 years heavy overhaul aircraft mechanic, 12 years AMSOIL dealer, 5 years Mechanical Engineer.