Transmission not shifting on 1997 Dodge Ram 2500

Shifts ok when cold. When warm, hesitates until RPM's 1500 or more. If it does shift into 3rd, it will immediately downshift and try to shift again. Am able to get home at 30 mph; no more.

Asked by for the 1997 Dodge Ram 2500
It sounds like your truck is going into a "limp" mode. Do you have a Check Engine Light on? Any warning lights?
Limp mode is a safety mode that your vehicles systems will send it into they detect certain things are wrong.

I would take this to a shop for diagnosis--sounds like a relatively major failure.
No warning lights. What is 'limp' mode?