I wonder if something more could be done with the "Evil Leaper" concept though.
At some point farther in the future (maybe 10 years from "present day" or so) Project Quantum Leap ran out of funding, was shut down and subsequently taken over by some corrupt organization/government agency/corporation. They managed to develop the technology further. Now they're able to control the leaps to some extent. They can can more or less determine to which year someone leaps (although sometimes this still goes wrong) and they can bring their leapers back home. And they start to use the technology to change history for their own purposes.
Sam's (or an other lead character's) mission would be to thwart the "evil leapers" attempts to manipulate history. He would also try to change the timeline in a way that Project Quantum Leap is never taken over by the bad guys in the first place. To raise the stakes a bit, let's say that Al (or whatever the lead character's companion is) will be murdered by the bad guys when they take over the project ten years from "now". That's the "big" wrong he tries to right during the course of the show.