'97 grand cherokee stalling

I have a very unusual probel w/my 97 grand cherokee ltd (6 cyl). seems it
has stumped the chrysler/jeep dealer I finally brought it for service. HAd
another mech try to diagnose and fix and after an induction coil, ign coil,
idle air valve and crank sensor replacement, seems the problem still
exists. The problem:Car will stall when at idle and difficult if not
impossible to restart. leave it alone for a few minutes it will restart.
engine could be cold or at operating temp. while driving it has also
stalled, but most times will "restart" enroute. Chrysler has had the car
for several weeks now and they are still scratching their heads. Thier
best best guess is that ther was carbon build up at the air idle valve.
They cleaned it, I drove it for a day and then it starts to stall again. I
had a multiple missfire code when it initially happened and you could tell
that when trying to restart it was miss firing. Recently the check engine
light came on and error code 21 (oxygen sensor voltage?) flashed. was on
for three days , when I brought it back to Chyrsler, the check engine light
no longer lit, don't know if the code was still there?
Anyway...anybody got any ideas? Chrysler sure doesn't!

 

loose wiring harness from the computer ?

 

They replaced an induction coil? That's a pretty neat trick,
considering it doesn't even have one.

You're not really clear as to who threw all the parts at it. Has the
dealer duplicated the problem? You said you had a misfire code. What
exactly was the code? The O2 fault could contribute to a performance
problem, but will not cause a hard/no start.

 

The parts were put in by a non-dealer mech that I have been using for
years. The induction coil, actually I believe it's called the pick up
coil in the distributor, my bad. The dealer has gotten it to stall by
running it for 8 hours (at idle) in the shop, but has not gotten any
error codes. That's why the initially had it for almost 2 weeks. They
told me to take the vehicle back and drive it for the weekend(no co-pilot
attached) they wanted to see if by cleaning the air idle of carbon that
would fix the problem. obviously it didn't and today is thursday, they
still haven't figured it out(brought it back in Saturday). I saw another
thread on this newsgroup about crank/cam sensors and sounds somewaht
similar to my problem. My original mech (afer throwning in all the
parts) said it was the PCM. Before I go that route, I thought Chrysler
would be able to pinpoint the exact problem, rather than throwing in a
PCM.