92 4.0 Jeep revving up after stopping - have to keep foot on brake
So this friend of mine has an automatic 92 cherokee 4wd with the 4.0 HO in it and for some reason when she comes to a stop light, 15-20 seconds later the engine will start revving up and she'll have to hold the brake down really hard to keep it from moving. It also I guess does it when she's in neutral and will rev up to like 2000 rpm and just stay there. I've poked around and only found a few things that hint maybe at the master cylinder, but I'm skeptical. Anyone see this before?