As stated by a few others here, break the corner on the bottom of the slide where it picks up the next round. If that leading edge is sharp, it can contribute to the problem you're having.
I have two P-07s. The first one was oversprung on the recoil spring. I was having the same problem you are having. My P-09 ran flawlessly. I noticed sided by side that my P-09 racked noticeably easier.
Some may recommend against this but I ground the small retainer off the end of the recoil spring assembly so I could remove the recoil spring and cut about 1/2" off of it. I think I removed a little more after some additional trial and error and ended up removing about 5/8" total. It's run flawlessly ever since.
Based on the problems you're having with it, I would guess that the gun hasn't seen a lot of rounds down the pipe. If it's had this problem since new, the previous owner likely got frustrated with it and didn't end up shooting it much.
I really think breaking the pickup edge of the slide and lightening the recoil spring will solve your problems. Please let us know what you find. These older guns are still good guns, you just have to work out a few bugs. Don't give up yet!!
