Here is the situation. My uncle has a 2000 GC. When he puts it in reverse, the engine will rev up. If you don't hold the brake real firm, the vehicle will take off. He had the transmission taken out and checked. Supposedly no problems there. And he also had the engine checked. Currenly no one knows what the problem is. I think it could be a vacuum leak, but I'm stumped. Any ideas would be greatly appreciated.