My Character Keeps Giving Exposition Dumps!!!

They say that when you really get good at writing, your characters write themselves, but I actually feel like my character is holding me back.
You see, I have gotten this crazy idea to try to be clever and introduce plot elements into the world in a way that feels both natural and where the audience can follow. But I have this one character who, every time before I can introduce plot elements naturally, comes in out of nowhere and gives an Exposition Dump in the biggest speed of verbal vomit you can imagine. It gotten so bad, I even tried killing him off, but he just came back as a ghost and is now giving all my characters Exposition Dump Jump Scares. I can't hold him back, I can't contain him, he just keeps coming and going whenever he pleases and is ruining my writing style. If tried taking a break, writing something else, but apparently my two stories take place in the same Universe because he's showing up there too. I regret killing him off, because now I feel I've given him too much power turning him into a ghost, so I tried rewriting the scene where he died so the one who killed him off decided not to kill him off, but now THAT character has decided to take a life of it's own, and now nothing I can do can prevent THAT character from killing him off, he's just too annoying to allow to live.

At this point I don't know what to do, I wanted to be the most best and clever writer ever, but because this one stupid annoying character, I feel I never will be.