thumping noise when cold startup

What is your question?

I have a 1996 ford ranger (4.0) 5 speed. Every fall/winter when it gets cold I hear a thumping noise when I start my truck. It never happens in the spring or summer. When I start up the truck sit idle, it thumps.

How long has your 1996 Ford Ranger had this problem?

last 2 years (only in cold weather)