Speedometer stopped working after changing the gear ratio to 4.56 from 3.55.

What is your question?

The speedometer started bouncing and jerking back and forth after I changed the gear ratio to 4.56 from 3.55 in my 1996 F150 4x4 XLT with 351w and automatic transmission. I recently lifted the truck 6" and it has 35x12.50R20 tires so it was a little shy on horsepower that is the reason for the gear change. The check engine light is not on and there are no engine codes. The cruise control tries to work but is has a difficult time following the speedometer and the engine revs up and down and is not steady.

What makes this problem better or worse?

Problem is constant

How long has your 1996 Ford F-150 had this problem?

For about 100 miles