Trans sticks overheats and stalls. What is going on and how to remedy

What is your question?

Trans sticks in 1st gear,then pops into 2nd and then overheats. Automatic transmission coolant drained and replaced. Idles in normal heat range without overheating. Just overheats while running.in traffic.

What makes this problem better or worse?

Cold start

How long has your 2000 Dodge Dakota had this problem?

A few weeks