1998 Jeep Cherokee 1998 Jeep Cherokee starts runs a while a

Several things could be happening here, you say you have an idle problem too, but I dont think that is what is shutting the vehicle. Off. What you should do in a case like this is try to get it to happen while at home so you can check fuel and spark, then you know what direction to go. But if I was to take an educated guess as to what may be the problem I would say, for the shutting off of the vehicle without warning, may very well be the crank position sensor.. The low idle, is possibly just a dirty throttlebody and throttle plate that needs some cleaning, the idle air control valve may be faulty, but I would definitely clean it first. Another thing you could check is the fuel pump relay, the shutting off of the vehicle, is mostlikely electrical. And what happens with the electrical components, like relays and sensors is when they get old. They get hot and then cause an open circuit, until it cools down again and completes the circuit then everything is back to normal, until it gets hot again