Why does my door pop when opened

[thebeast61]

My driver door makes a loud popping noies when opened. I have sprayed lubricant on everything that I can see. It appears to be coming from the thingamabob (yes thats a technical term) that goes from the body to the inside of the door. Its about halfway down the door. I guess its to keep the door from going open to far and hitting the fender. Could this be broken inside or is there some kind of adjustment I can make?
Its a 61 GMC