I have a 2000 Mailibu.  About two months ago I was driving home from
work on the highway.  I felt my car lose power.  I looked and my RPM
gage was dropping and pressing the gas did not help.  The engine was
still on.  I managed to pull to side of highway and as soon as car
came to complete stop the car died and would not start back up.  My
husband figured it was time for a Tune Up on the car so he changed all
the wires and plugs.  That seemed to work until about 1 week ago.  I
was driving to work the last wednesday and it did it again.  The car
lost power, I pulled to side of highway and it shut off.  However,
after it sat for a minute I was able to drive it the rest of way to
work (I was almost off highway).
I took it to mechanic after work and they could not find anything
wrong with it.  Took the car home and tried to drive to work the next
morning.  I did not get very far on the highway.  Maybe 4 miles.  I
waited and it started back up, but then died again as I was exiting
the highway sitting at a light.  It was towed to mechanic.  The tests
still show nothing.  They replaced the Crank Shaft Pulley and the
sensor thinking that was the problem.  Got the car back - tried to
drive to work in the morning and it did it again.  The mechanic has
had it for two days trying to get the problem to reproduce with no
luck.  They said they would fix it for free but they won’t do the work
unless they know exactly what is wrong.  The mechanic is not the
dealer.
Any suggestions?  I don’t know what to do anymore.