Odd sound coming from the front passanger door kick area.

[Henry Suarez]

It sounds like a small wood pecker is hiding in the foot rest/ bottom of the front door area. It only occurs when the truck is stopped (as soon as I accelerate it goes away). It happens if ac is on or off and the truck hot or cold. I think my running board might be loose but I wanted to check and see if anyone else has experienced this problem.