i have a '98 Grand Cherokee that likes to shut off while i am driving it. Mostly it happens while idling, driving slowly, or slowing down to stop, although it has also happened on the freeway a few times. Sometimes it starts right back up and other times it takes a few tries. i have had sensors tested, my coil replaced (twice), my alternator checked and no one knows what the problem is. This has been occurring for almost a year. Within the last month or so an obnoxious rattling sound has started coming from under the car when i start it, shift into reverse, and when it tries to die on me. Any ideas?? i recently read something about catalytic converters making an engine shut off if they are clogged. Could that be the problem?
Any help would be much appreciated, especially if it was presented in such a way that a 5 year old could understand because i'm not very mechanically inclined. Thank you!!

no it would not be your catalytic converter causing your car to shut down. if i where to throw parts at it i would go in this order. 1 replace crank shaft position sensor(ckp) 2 replace idle air control valve(iac) 3 throttle position sensor (tps). if that doesn't fix it 4 slap an upstream 02 sensor on it, hell id just 5,6,7,8,9,,,, replace every frickin sensor on the damn car. then when it still is not fixed ill slap a brand spankin new 700 dollar pcm in it, after all we're just guessing right. and when that that does not fix it ill kick a big dent in the stupid finder panel before i rip all of the f*&^ wiring out with a steak knife, take a cupel stabs at the tires and give it a good beat down with my fist through the window. screw it, im gunna get this p.o.s. back together and use it to run down that f'n parts boy, him and his little smirk! time to torch this cream puff, along with the evidence. better report it stolen just incase they find it. then you could say you didn't do it. better just get some guns, just in case. :banghead:

In all seriousness, I would replace the crank shaft position sensor and see if that fixes it. Maybe the iac(i doubt its that, but could be) I would not replace anything else with out checking for codes and looking at sensor values with a scan tool.
Do you have any other problems? Check engine light, poor fuel mileage. Does the engine jerk or sputter before it dies?

i do have poor mileage but it is, after all, a jeep cherokee and it doesn't seem abnormally low. My check engine light is not on, but my engine occassionally will jerk and sputter before it dies.

I had a similar problem some time back. Mine was different because the check engine light came. It was an o2 sensor.
I bought the car(98 grand cherokee) with a cracked exhaust manifold and some other problems. It as a project so i never drove the car for more then a block or two. I fixed the exhaust and everything else. As took the car home the problem started. i got about half way home when it sputtered and died the first time, the car started right back up and was fine . two days later it died again on the highway, it sputtered and jerked and the check engine light came (o2 sensor code) i got off the freeway and started it right back up, but every time i hit the gas it would just cough. let it sit for a couple of minutes , started it back up and ran just fine to the auto-parts store. after i replaced the sensor everything was fine. i think what happened in my case was that the massive exhaust leak took out the sensor (hot and cold air?) OBD 2 cars are way more sensitive then the old ones with stuff like that.

If this sounds like your car i would be suspect of the Oxygen(o2) sensor. If it just dies with out all of the other drama, i would look further into the Crankshaft Position Sensor. but it still could be other factors so lets try unplugging your battery for 10-15 minutes, it will reset all of your drive cycle monitors, reset your k.a.m. and fuel strategy. Then lets see if we can get a check engine light when the system self checks and re-strategizes

If you can afford it, try asking your repair facility if they have a data recorder. They plug into your d.l.c. and record engine management data. When the problem happens you push a button and it saves a recording of the information 1 minute(or so) before and after the event. If your repair facility does not have one, i suggest you find one that does.