I also have this problem with my 2000 Xterra. It has done this ever since I bought the vehicle several years ago. Also, sometimes the shifts are nice and solid, but other times it seems to shift real sloppy almost like it is wanting to slip. The only thing is that it seems to be completely random. It doesn't matter if the engine is cold or warm. Does anyone else have this problem, and if so, how did you correct it? I have followed my maintenance schedule religiously and have always changed the fluids according to the manual stated intervals. Someone please help?