LOOKING FOR CAUSE OF HESITATION IN '99 JEEP WRANGLER

I have a new '99 Jeep Wrangler Sahara that has a hesitation in the engine
while driving.  It occurs all of the time and is much more apparent when
driving up a long freeway hill in 4th or 5th gear under a load.  It is not
cycling like a bad spark plug but random and often.  I have taken it into my
dealer, Skagit Auto Center, four times so far and they have replaced the spark
plugs, spark plug wires and the crankshaft position sensor.  They finally sent
the computer recording off to Chrysler for their help but to date, nobody can
figure it out.  Do you or someone you know have any knowledge of what is going
on?  Surely, I am not the first person to have this problem.  All comments or
inputs are appreciated...