Speedo jumps //tranny downshifts

[MAC55]

Hello .....i have owned a 96 xlt 4.0 auto 4wd control trac for years,never had a problem like this. After driving for approx 30 minutes the speedo starts jumping erratically initially starting as i go over 40 mph. Then the tranny downshifts to 4th-then back to 5th, if i let my foot off the gas the speedo goes back to normal. As soon as i press on the gas the speedo acts up again .the longer i drive it the worse the speedo and erratic shifting gets. Eventually the speedo jumps from the moment i start from a stop, but again if i let off the gas it goes up to the correct mph. I replaced the vss in the transfer case..no help.i changed out the instrument cluster..no help either. Any ideas would be appreciated

 

[MAC55]

Found the problem....the wire(s) approx 2 inches from speed sensor connector and covered by insulating tape were broken almost in two. Must have been due to age I guess. At any rate I repaired them and everything is back to normal. Thanks for no help or suggestions!