Why is my transmission slipping in 99 dodge ram 1500

What is your question?

Driving along and transmission slips and rpm goes up and I get off the gas and let it drop and accelerate and it shifts. Dosen't do it often. What may the problem. And also the speed odometer stop working.

What makes this problem better or worse?

Worse when hot.

How long has your 1999 Dodge Ram 1500 had this problem?

A month. But only happens occasionally.