1998 grand Cherokee Sometimes it will die while idling it always starts back up. Sometimes while driving it will hiccup and keep going. It doesn't do it all the time just every once in a while

SOURCE: 1988 jeep cherokee idles rough, and will die while driving

Sounds like it could be a bad map sensor.
Black smoke?

SOURCE: no spark/wont start

i have a 98 and it has a distributor but it could be a fuel issue more than a spark if you have a fuel pressure gauge and check it.should be above 30 psi to me it sounds like a fuel pump thats bad

SOURCE: Having trouble keeping my 98 jeep grand cherokee running

i recommend cleaning the throttle plates. they are located unter the intake hose form the engine to the air filter housing. if you open them with the engine not runniong you will see they will be covered in carbon. use a good carb cleaner and a rag to wipe them clean

SOURCE: 98 jeep grand cherokee dies and starts back

replace the crank angle sensor and this should cure your problem

SOURCE: 1998 Jeep Grand Cherokee shuts down while driving.

97 cherokee crank sensor replaced, still shuts off, code 351