Starts as soon as cranked, runs for a few seconds and dies. What's wrong?

This is very normal.
All jeeps do this. when bad.
first off all engine stall when not tuned up or BAD.

same answer for 100 years running.
top of list is what, per operator guide, filters and spark parts.
see that list for 60,000 miles, its REAL.
now the normal bad deal
all jeeps 93+ have a feature, called ASD
this prevents crash and burn as een on TV.
and is by laws.....
you dont want fuel flowing with no spark. so...... ASD is born.
automatic shut down relay
NCABR (no crash and burn relay, works too){joking}
if you are tuned up, are you. and fuel fresh, is it?
then the scan tool told you why the ASD dropped ,did it?


http://www.fixkick.com/Jeeps/ASD.html

there are really over 50 causes of stalls.
a huge list
we do simple tests, 1 to 10 and bam, the answer
a.k.a , gathering evidence.

do you want us to gue$$. or test.???
its your call.
the tests take tools. if working with no tools this will be expensive.
do the flash code tests yet.
sometimes this works, I dont like it, as key off erases some errors.

the key one off 3 times trick

http://autorepair.about.com/library/a/1h/bl903h.htm

one smart guy i know, got so grief stricken by this.
I do fell the pain
He bought a new ASD, for $10 (a relay)
then ripped the top off the old, he kinda skeletonized, it.
so it sill works but can see the GUTS (savvy huh?)
had son crank car, he watches it like hawk.
sees it close (as it starts, 1,2,3 seconds and BAM)
just one 1/10 a second, before the stall the ASD DROPS
now for 100% sure i KNOWS it drops
and knows 1 more thing, what is that,
answer, the PCM dropping it on purpose
and guess what, he now knows for fact the PCM recorded that error and the scan tool will see it.
my innova 3140 can. see the 93 to 95 errors.
96 year plus, all scan tools can..

lets not say the ASD didnt trop
that means the engine misfired so bad the ECU can not keep it running by adding fuel and more AIR (ISC) valve air.
its a bad running engine. and gets more complex.
but this is just the beginning in this case.
see>?

Clean the throttle body bore and butterfly plate of any carbon/black deposits as they can restrict idle ability .