I have a dodge ram 1500 that shortly after I start it - I hear a click - sounds like something is cycling, and after about 20 or 30 seconds a click and it stops. It happens about every minute when it is ideling. I do now know what is happening when it is actually running.

Any ideas?

Likely, it is associated with the fuel injection system. It's not uncommon for clicking and air sounds to come from the fuel injection system, until the engine warms up.

Is the truck equipped with A/C? If it's low on freon, it could be causing the compressor to shut on and off, which may be the clicking that you're hearing.

This could also be the electric fan cycling on and off to keep the vehicle cool. When you are idling and have no air flowing over your radiator then the fan kicks on to keep it cool. Open your hood and see if the fan goes on and off in conjunction with the clicks.