I have a friend with a 94 Grand Cherokee that had a similar type of problem...but his ZJ didn't sputter but just died like is some one turned the key off.
I called him as I started writing this and he said have you try this first, when your getting the sputtering stop and disconnect the map sensor for a few minutes and reconnect it (the electrical part not the vacuum), this should reset the system. It should stop it for 40-60 miles, if it does then replace the MAP sensor. If it doesn't then you have a faulty computer.
If it is the computer, first off don't go to the stealership for a replacement, go down to your local Autozone and order in a replacement from them, they use an after market company that goes in and replaces the feed back diode from the map and Auto shut down relay and increases the heat dissipater off the main CPU and shield the wiring better. Once they have it in you can pull yours and exchange it with theres...I was told it was 250$ but comes with a life time warranty. It has cured his problem and now has no fear of taking it wheeling.