4 Wheel Drive/SUVs: transmission 1999 chev Z71 5.6, whip lash, transmission changes

Question
OCCASIONALLY WHEN THIS TRANSMISSION CHANGES FROM
FIRST TO 2ND AND 3RD IT WILL ALMOST GIVE ME A WHIP-LASH IT IS CHANGING SO HARD,AFTER I STOP, CUT
THE MOTOR OFF AND LET IT SET FOR AWHILE,IT IS O.K.
IT IS AN AUTOMATIC WITH O/D.     
             HELP!
   THANKS
          DAVID

Answer
Hi David, it could be a couple different things.  First, make sure the tranny fluid is ok (full to the marker and does not smell burnt).  Second, if it has been 50,000 miles or so since you serviced the tranny, you may want to consider a good, complete service.
And lastly, I hate to say it, but I think your 99 is computer controlled shifting.  Sometimes the computer goes whacky and needs work.

Do the fluid things first.  You can also check some Chevy sites in the Internet.  Get to them from my web site:
www.delalbright.com and follow the links to Vehicle Modificiations and Fixits.
Good luck, sorry I could not help more, Del