Jeep Repair: 1997 GRAND CHAROKEE LIMITED, jeep cherokee limited, crank sensor

Question
MY FAMILY HAS ALWAYS DROVE A JEEP. MY DAD, MOM, SISTER, AND ME. WE HAVE NEVER HAD ANY PROBLEMS UNTIL NOW. I HAVE HAD THIS PARTICULAR JEEP ABOUT 1 1/2, 1997 GRAND JEEP CHEROKEE LIMITED AND HAVE ONLY GOT TO DRIVE IT ABOUT 3 OF THOSE  MONTHS. SOMETIMES IT WILL RUN PERFECT OTHER TIMES IT DOESN'T. YOU WILL BE DRIVING DOWN THE ROAD AND ALL OF A SUDDEN IT CUTS OFF ON YOU AND SOMETIME BACKFIRES. ONCE IT CUTS OFF IT IS VERY HARD TO START BACK. IF YOU ARE ON THE FREEWAY, ITS FINE. BUT THE MINUTE YOU GET OFF THE EXIT IT CUTS OFF. I HAVE TOOK IT TO 4 DIFFERENT MECHANICS AND PAID OVER $4000 AND NOBODY KNOWS WHAT IT IS. I HAVE HAD ALMOST EVERYTHING REPLACED INCLUDING THE COMPUTER. I FOUND A NEW MECHANIC AND HE SEEMS TO THINK ITS THE CRANK SENSOR ALONG WITH ANOTHER GUY, SO MAYBE ILL HAVE LUCK THIS TIME. I AM TO THE POINT WHERE I ABSOLUTELY HATE JEEPS. DOES ANYONE HAVE ANY IDEAS WHAT IT COULD BE???

Answer
need some info on what have been checked and done first   there could be a list of 20 different things that can cause this   with out some info or diog done to it  I would be doing no more good then any of the other people that has just thrown parts at it.