My V-6 2000 Malibu cuts off sometimes at high speeds (65MPH), and
often on bridges.  It usually dies near enough to the top that I can
coast over and off the bridge.  After a few minutes, it starts up
again.  It doesn't happen often...two to three times a week.
  Once, it died early on the way up the bridge.  In 30 minutes of
trying, it would not start.  A good policewoman used her car to push
me over the top and I coasted to the bottom and arranged a tow.  In a
few minutes, it started right up.
  I still had it towed to the nearest dealer as I did not want to
repeat the experience of being on that bridge at the mercy of
tractor-trailers who swerved away from me at the last second.
  The dealer could not find a problem with it.  I explained the
circumstances when it fails...high speed or bridges, and the rpm
flattens and then the engine shuts off.  The service manager let me
talk to the mechanic and I asked him if he checked the fuel system.
He told me that the computer did not indicate any problem there, so he
did not.  In their favor, the service manager "no-charged" the $83
diagnostic fee because I was unhappy about the lack of resolution.
  This problem has been going on intermittently for over six months,
and a few weeks ago I paid to have the fuel filter replaced when I had
the emergency light recall done.  It still does it.
  Any ideas?  Thanks.

  I have also seen posts here about other  issues with the Malibu
that I have experienced:
  Fan motor only works on high.  Actually, positions 1 and 2 seem to
drop out first.  There is a resistor on the passenger side where the
firewall meets the floor.  It costs $10 to $20 and is mounted  by two
screws and is kind of hard to get to.  Replacing it fixed my problem.
  Coolant leak.  Twice I ran low on coolant.  An independent mechanic
told me that the Malibu is famous for a defective intake manifold
gasket that leaks.  He showed me that small leak.  Having the manifold
gasket replaced fixed that.
  Signal problems.  Often using my turn signals just made a buzzing
noise and they didn't work.  Initially, banging on the console near
the emergency flasher switch would get them working.  Finally they did
not work at all, so I let Chevrolet do its emergency flasher switch
replacement recall.  That fixed it.
  Hope this helps some.