Speedometer / transmission issue

I have a 1994 4Runner with 3.0 and auto trans. When I drive, everything is ok until I have gone for about 5 minutes. Then the speedometer gets erratic and bounces all over and gears start jumping around. Almost like the trans is slipping. But it drives and shifts fine for the first few minutes. I have replaced the speed sensor in the transfer case (mount was broken in old one) and I replaced all the solenoids. Any other ideas?

 

A official welcome to yah. Welcome from Central Penciltucky

 

That happened to mine many years ago and finally gave out completely. Ended up being the actually speedometer cluster. Cost me $400 to replace at dealership but that was back in the early 2000's.