My 96 mercury sable 3.0 l sohc the transmission is acting wild now all a suddden have owned it for about 3 months and from first to second is usually ok sometimes like sticking it seems ???? and every time i stop or hit a light almost evry tinme its last down shift is a clunk kinda ? had similar problem with a nissan needed to weld transmission onto the mounts ? inm wondering if i change the filter will it be better ?

SOURCE: need wiring diagram for radio on 96 mercury sable

http://www.the12volt.com/installbay/stereodetail/1500.html

SOURCE: 99 sable

The problem is with your VSS (Vehicle Speed Sensor) located on the passenger side axle housing. It will cost approx. $300 to have Ford dealer do it.

SOURCE: Transmission shift problem

I would suggest changing the fluid and filter andhaving the bands adjusted.

SOURCE: I have a 2004 Mercury Mountaineer. Sometimes when

you probably should change the transmission fluid and filter with that many miles on it.

SOURCE: 1997 mercury sable won't shift into overdrive

first of all, check the kickdown cable to transmission. it may be out of adjustment. or just bad.if its the cable out of adjustment, it is sure cheaper then a tranny.