After rereading your post, something came back to me that I hadn't thought about in a very long time. It wasn't the CLP. It may have been a lack of CLP.
The problem you describe happened to me shortly after buying my 19. I took it completely apart and cleaned every part. I then promptly put it back together without any CLP on it. I then took the slide back off, removed the barrel and spring and put a drop of CLP on the rails and the barrel hood. I then put it back together and started dry-firing it. (Did you see the part I missed?) After a dozen or so pulls the trigger starts to drag like an anchor. My first thought was that the gun and its trigger were crap!
I stopped though and looked back at the owner's manual. I started at the beginning and reread the instructions untill I got to the part about a drop of oil (You can see it coming can't you?) on the connector!
I said to myself "I meant to do that to see what would happen. Yeah, that's it, it was a test!" (Nobody was fooled, not even me.)
I put a drop of CLP on the connector and
VIOLA!, the damned thing worked again just like it was supposed to!
(I hate when I do that!)
This may be what happened to your gun.
You see? We are like brothers!