Internet gunsmithing is never easy. Are you 100% positive that you haven't got some sort of trigger stop installed in that pistol? (Look behind the left-hand side, 'drop safety wing'. Do you see a little set screw?)
Here's what's happening: There is a downward angle towards the rear of the slide on a 4.5# (nominal 3.5#) connector. The trigger bar is proceeding to this point and, then, getting hung up (for whatever reason) on the extreme downward slope of the connector bar. It's just hanging there until you shake the pistol; and, voila, the trigger bar's, 'bird's head' suddenly slips off the connector, and the FP lug snaps forward firing the pistol.
Something, I have no idea what, is impeding the movement of the trigger bar. You don't have a connector problem; what you have is a trigger bar and, possibly, a trigger housing problem. Me? I'd change the trigger housing unit, first. If that didn't work, then I'd change the trigger bar, too.
Here's that angle I'm talking about