My P380 was bought used, but ran great for a long time. Then it started having the kind of issues you mention. Sent in to Kahr MULTIPLE times, they tried everything, and it finally turned out to be the frame which had "fatigued" for some reason. Your problem is probably not that, but problems with these can be hard to isolate and need many attempts to solve. Here's the point:
I got frustrated and bought another while waiting (a CW380.) Since then I'm a believer in redundancy. I carry one, keep the other in the range bag, and rotate them. (I actually now have 3 because of the irresistible sale on black P380s a few years ago.) No problems for a long time, but if and when one has any issue, it will go straight back to Kahr, and back again as many times as it takes. Having another to carry while waiting drastically reduces the inconvenience and frustration.
Rest in peace Muggsy
"Individual Muslims may show splendid qualities, but the influence of the religion paralyses the social development of those who follow it. No stronger retrograde force exists in the world." Winston Churchill 1899