jeep slow to shift into reverse

So I posted awhile ago that my Jeep was slow shifting into reverse. I flushed the tranny and I am still having the same problem. I have the Selec-Trac 4WD set-up. It drives me crazy because I shift it into reverse and it takes almost a full second to shift into reverse. And even when it feels like it is in reverse, I hit the gas and it takes almost a half second for the Jeep to start moving backwards. I don't have any other problems with any other gears and I have owned this Jeep for four years now and the problem hasn't gotten any worse or any better. Could it be a bad linkage or bad sensor or something? Any advice would be great. Thanks.

It's a 1998 Grand Cherokee, I6, Selec-Trac 4WD