one of mine does that same thing. I haven't looked at it in detail but I think probably a weld broke and doesn't hold it in place. It's more of a hard pop. I just don't open the door all of the way and it's fine. Too cold to do anything about it right now.
I have the same problem on my 92 and I removed the front fender to take a look. The bracket is inside of the welded door frame and inaccessible. More disassembly is required and I'm not sure from where. I'm just not going to open the door all the way anymore.
I have the same problem with my passenger door. But since I don't sit there anyways, it rarely bugs me...t's only when I'm parked around lots of people that I wouldn't want to hear that loud POP! Besides that, lambo upgrade? j/p
This just happened on my driver side door today. The hinge that is attached to the chassis of the car is not secured anymore. It moves from side to side when the door is opened, but it sounds like the pop is coming from inside the door around the arm, and not the hinge connection. It looks like it's been tack welded before, so I'll try that and see if it stops it.