I don’t have a recipe for you, but I tried making a peanut butter cake once. I don’t know a whole lot now, but I really knew NOTHING then, so I simply subbed peanut butter for the butter and I got a very, very dense cake. I think it’s because PB contributes protein, maybe fiber, and, of course, less fat, all of which will toughen a cake. That might be why your PB cupcakes have been less satisfactory than you might hope.
I can’t really help you unless that info helps you to play with an existing recipe—finding a way to add lightness and moisture.
That said, maybe you can make a ‘regular’ cupcake and then make a peanut butter mousse to fill them and top with maybe a PB/cream cheese frosting? (Or chocolate, of course.)
Cupcake liners coming off have been discussed over and over here—I don’t know if a conclusion was ever arrived at! I don’t make cuppies myself, so I can’t contribute there, either.