I have a 1993 Taurus GL 3.8 with approx. 91k miles, just recently the car started shifting erratically. When I am driving the car for no reason the car will sometimes drop to a lower gear and on one occasion has dropped into neutral. Also when I accelerate hard sometimes the car will shudder (but doesn't make a grinding sound) like it is in a higher gear than it should be in. I checked the fluid and its color is good and does not smell burnt at all. I took it to a vehicle shop and had them run the codes on the tranny and it came up with a faulty vehicle speed sensor. If this were the case wouldn't my speedometer stop working as well since the speedometer pulls its speed from the sensor? I am also contemplating having the fluid replaced and a new filter installed since the mileage is so high. What would be a good ATF fluid to use? I keep hearing Mercon V is a recommended fluid. Thanks!